diff --git a/app/Modules/Inventory/Controllers/ProductController.php b/app/Modules/Inventory/Controllers/ProductController.php
index 22a7319..a1d9a30 100644
--- a/app/Modules/Inventory/Controllers/ProductController.php
+++ b/app/Modules/Inventory/Controllers/ProductController.php
@@ -197,6 +197,10 @@ class ProductController extends Controller
             $validated['code'] = $this->generateRandomCode();
         }
 
+        if (empty($validated['barcode'])) {
+            $validated['barcode'] = $this->generateRandomBarcode();
+        }
+
         $product = Product::create($validated);
 
         return redirect()->route('products.index')->with('success', '商品已建立');
@@ -260,6 +264,10 @@ class ProductController extends Controller
             $validated['code'] = $this->generateRandomCode();
         }
 
+        if (empty($validated['barcode'])) {
+            $validated['barcode'] = $this->generateRandomBarcode();
+        }
+
         $product->update($validated);
 
         if ($request->input('from') === 'show') {
@@ -328,4 +336,21 @@ class ProductController extends Controller
 
         return $code;
     }
+
+    /**
+     * 生成隨機 13 碼條碼 (純數字)
+     */
+    private function generateRandomBarcode(): string
+    {
+        $barcode = '';
+        
+        do {
+            $barcode = '';
+            for ($i = 0; $i < 13; $i++) {
+                $barcode .= rand(0, 9);
+            }
+        } while (Product::where('barcode', $barcode)->exists());
+
+        return $barcode;
+    }
 }
diff --git a/app/Modules/Inventory/Exports/InstructionSheet.php b/app/Modules/Inventory/Exports/InstructionSheet.php
new file mode 100644
index 0000000..d37ae65
--- /dev/null
+++ b/app/Modules/Inventory/Exports/InstructionSheet.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Modules\Inventory\Exports;
+
+use Maatwebsite\Excel\Concerns\FromCollection;
+use Maatwebsite\Excel\Concerns\WithHeadings;
+use Maatwebsite\Excel\Concerns\WithTitle;
+use Maatwebsite\Excel\Concerns\WithStyles;
+use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+
+class InstructionSheet implements FromCollection, WithHeadings, WithTitle, WithStyles
+{
+    public function title(): string
+    {
+        return '填寫說明';
+    }
+
+    public function headings(): array
+    {
+        return [
+            '欄位名稱',
+            '是否必填',
+            '填寫說明',
+        ];
+    }
+
+    public function collection()
+    {
+        return collect([
+            ['商品代號', '選填', '2-8 碼，若未填寫系統將自動生成。若代號已存在，將更新該商品資料。'],
+            ['條碼', '選填', '13 碼數字，若未填寫系統將自動生成。若條碼已存在（優先比對），將更新該商品資料。'],
+            ['商品名稱', '必填', '請填寫完整商品名稱。'],
+            ['類別名稱', '必填', '必須為系統中已存在的類別名稱（如：飲品）。'],
+            ['品牌', '選填', '商品品牌名稱。'],
+            ['規格', '選填', '商品規格描述（如：25kg/袋）。'],
+            ['基本單位', '必填', '必須為系統中已存在的單位名稱（如：瓶、個）。'],
+            ['大單位', '選填', '若有大單位換算請填寫（如：箱）。'],
+            ['換算率', '若有大單位則必填', '1 個大單位等於多少個基本單位。'],
+            ['成本價', '選填', '數字，預設為 0。'],
+            ['售價', '選填', '數字，預設為 0。'],
+            ['會員價', '選填', '數字，預設為 0。'],
+            ['批發價', '選填', '數字，預設為 0。'],
+        ]);
+    }
+
+    public function styles(Worksheet $sheet)
+    {
+        return [
+            // 第一行標題粗體
+            1 => ['font' => ['bold' => true]],
+            // 欄位寬度自動
+        ];
+    }
+}
diff --git a/app/Modules/Inventory/Exports/ProductImportSheet.php b/app/Modules/Inventory/Exports/ProductImportSheet.php
new file mode 100644
index 0000000..4b0570e
--- /dev/null
+++ b/app/Modules/Inventory/Exports/ProductImportSheet.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace App\Modules\Inventory\Exports;
+
+use Maatwebsite\Excel\Concerns\WithHeadings;
+use Maatwebsite\Excel\Concerns\WithColumnFormatting;
+use Maatwebsite\Excel\Concerns\WithTitle;
+use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
+
+class ProductImportSheet implements WithHeadings, WithColumnFormatting, WithTitle
+{
+    public function title(): string
+    {
+        return '商品匯入';
+    }
+
+    public function headings(): array
+    {
+        return [
+            '商品代號(選填)',
+            '條碼(選填)',
+            '商品名稱',
+            '類別名稱',
+            '品牌',
+            '規格',
+            '基本單位',
+            '大單位',
+            '換算率',
+            '成本價',
+            '售價',
+            '會員價',
+            '批發價',
+        ];
+    }
+
+    public function columnFormats(): array
+    {
+        return [
+            'A' => NumberFormat::FORMAT_TEXT, // 商品代號
+            'B' => NumberFormat::FORMAT_TEXT, // 條碼
+        ];
+    }
+}
diff --git a/app/Modules/Inventory/Exports/ProductTemplateExport.php b/app/Modules/Inventory/Exports/ProductTemplateExport.php
index 6d04e40..5321e74 100644
--- a/app/Modules/Inventory/Exports/ProductTemplateExport.php
+++ b/app/Modules/Inventory/Exports/ProductTemplateExport.php
@@ -2,39 +2,15 @@
 
 namespace App\Modules\Inventory\Exports;
 
-use Maatwebsite\Excel\Concerns\WithHeadings;
+use Maatwebsite\Excel\Concerns\WithMultipleSheets;
 
-use Maatwebsite\Excel\Concerns\WithColumnFormatting;
-// use Maatwebsite\Excel\Concerns\WithHeadings;
-use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
-
-class ProductTemplateExport implements WithHeadings, WithColumnFormatting
+class ProductTemplateExport implements WithMultipleSheets
 {
-    public function headings(): array
+    public function sheets(): array
     {
         return [
-            '商品代號',
-            '條碼',
-            '商品名稱',
-            '類別名稱',
-            '品牌',
-            '規格',
-            '基本單位',
-            '大單位',
-            '換算率',
-            '成本價',
-            '售價',
-            '會員價',
-            '批發價',
-
-        ];
-    }
-
-    public function columnFormats(): array
-    {
-        return [
-            'A' => NumberFormat::FORMAT_TEXT, // 商品代號
-            'B' => NumberFormat::FORMAT_TEXT, // 條碼
+            new ProductImportSheet(),
+            new InstructionSheet(),
         ];
     }
 }
diff --git a/app/Modules/Inventory/Imports/ProductImport.php b/app/Modules/Inventory/Imports/ProductImport.php
index 9836d32..4dafbaf 100644
--- a/app/Modules/Inventory/Imports/ProductImport.php
+++ b/app/Modules/Inventory/Imports/ProductImport.php
@@ -57,21 +57,25 @@ class ProductImport implements ToModel, WithHeadingRow, WithValidation, WithMapp
         $baseUnitId = $this->units[$row['基本單位']] ?? null;
         $largeUnitId = isset($row['大單位']) ? ($this->units[$row['大單位']] ?? null) : null;
 
-
         // 若必要關聯找不到，理論上 Validation 會攔截，但此處做防禦性編程
         if (!$categoryId || !$baseUnitId) {
             return null;
         }
 
-        // 處理商品代號：若為空則自動生成
         $code = $row['商品代號'] ?? null;
-        if (empty($code)) {
-            $code = $this->generateRandomCode();
+        $barcode = $row['條碼'] ?? null;
+
+        // Upsert 邏輯：優先以條碼查找，次之以商品代號查找
+        $product = null;
+        if (!empty($barcode)) {
+            $product = Product::where('barcode', $barcode)->first();
         }
 
-        return new Product([
-            'code' => $code,
-            'barcode' => $row['條碼'],
+        if (!$product && !empty($code)) {
+            $product = Product::where('code', $code)->first();
+        }
+
+        $data = [
             'name' => $row['商品名稱'],
             'category_id' => $categoryId,
             'brand' => $row['品牌'] ?? null,
@@ -84,7 +88,26 @@ class ProductImport implements ToModel, WithHeadingRow, WithValidation, WithMapp
             'price' => $row['售價'] ?? null,
             'member_price' => $row['會員價'] ?? null,
             'wholesale_price' => $row['批發價'] ?? null,
-        ]);
+        ];
+
+        if ($product) {
+            // 更新現有商品
+            $product->update($data);
+            return null; // 返回 null 以避免 Maatwebsite/Excel 嘗試再次 insert
+        }
+
+        // 建立新商品：處理代碼與條碼自動生成
+        if (empty($code)) {
+            $code = $this->generateRandomCode();
+        }
+        if (empty($barcode)) {
+            $barcode = $this->generateRandomBarcode();
+        }
+
+        $data['code'] = $code;
+        $data['barcode'] = $barcode;
+
+        return new Product($data);
     }
 
     /**
@@ -105,11 +128,28 @@ class ProductImport implements ToModel, WithHeadingRow, WithValidation, WithMapp
         return $code;
     }
 
+    /**
+     * 生成隨機 13 碼條碼 (純數字)
+     */
+    private function generateRandomBarcode(): string
+    {
+        $barcode = '';
+        
+        do {
+            $barcode = '';
+            for ($i = 0; $i < 13; $i++) {
+                $barcode .= rand(0, 9);
+            }
+        } while (Product::where('barcode', $barcode)->exists());
+
+        return $barcode;
+    }
+
     public function rules(): array
     {
         return [
-            '商品代號' => ['nullable', 'string', 'min:2', 'max:8', 'unique:products,code'],
-            '條碼' => ['required', 'string', 'unique:products,barcode'],
+            '商品代號' => ['nullable', 'string', 'min:2', 'max:8'],
+            '條碼' => ['nullable', 'string'],
             '商品名稱' => ['required', 'string'],
             '類別名稱' => ['required', function($attribute, $value, $fail) {
                 if (!isset($this->categories[$value])) {
diff --git a/resources/js/Components/Product/ProductForm.tsx b/resources/js/Components/Product/ProductForm.tsx
index 816198a..856dc2a 100644
--- a/resources/js/Components/Product/ProductForm.tsx
+++ b/resources/js/Components/Product/ProductForm.tsx
@@ -62,8 +62,11 @@ export default function ProductForm({
     };
 
     const generateRandomBarcode = () => {
-        const randomDigits = Math.floor(Math.random() * 9000000000) + 1000000000;
-        setData("barcode", randomDigits.toString());
+        let result = "";
+        for (let i = 0; i < 13; i++) {
+            result += Math.floor(Math.random() * 10).toString();
+        }
+        setData("barcode", result);
     };
 
     const generateRandomCode = () => {
@@ -150,7 +153,7 @@ export default function ProductForm({
 
                     <div className="space-y-2">
                         <Label htmlFor="barcode">
-                            條碼編號 <span className="text-red-500">*</span>
+                            條碼編號 <span className="text-gray-400 font-normal">(選填，未填將自動生成)</span>
                         </Label>
                         <div className="flex gap-2">
                             <Input
diff --git a/resources/js/Components/Product/ProductImportDialog.tsx b/resources/js/Components/Product/ProductImportDialog.tsx
index f04f23d..25db7ce 100644
--- a/resources/js/Components/Product/ProductImportDialog.tsx
+++ b/resources/js/Components/Product/ProductImportDialog.tsx
@@ -111,9 +111,11 @@ export default function ProductImportDialog({ open, onOpenChange }: ProductImpor
               <AccordionContent>
                 <div className="text-sm text-gray-600 space-y-2 pb-2 pl-6">
                   <ul className="list-disc space-y-1">
-                    <li><span className="font-medium text-gray-700">必填欄位</span>：商品名稱、類別名稱、基本單位、條碼。</li>
+                    <li><span className="font-medium text-gray-700">必填欄位</span>：商品名稱、類別名稱、基本單位。</li>
                     <li><span className="font-medium text-gray-700">商品代號</span>：2-8 碼，非必填（未填將自動生成，大寫英文+數字 8 碼）。</li>
-                    <li><span className="font-medium text-gray-700">唯一性</span>：商品代號（若有填寫）與條碼不可與現有資料重複。</li>
+                    <li><span className="font-medium text-gray-700">條碼</span>：13 碼數字，非必填（未填將自動生成）。</li>
+                    <li><span className="font-medium text-gray-700">補充說明</span>：詳細規則亦可於 Excel 範本的<strong>「填寫說明」</strong>工作表中查看。</li>
+                    <li><span className="font-medium text-gray-700">更新機制</span>：若系統中已有相同<strong>「條碼」</strong>或<strong>「商品代號」</strong>，系統將自動更新該筆資料，不會重複建立。</li>
                     <li><span className="font-medium text-gray-700">自動關聯</span>：類別與單位請填寫系統當前存在的「名稱」（如：飲品、瓶）。</li>
                     <li><span className="font-medium text-gray-700">大單位</span>：若填寫大單位，則「換算率」為必填（需大於 0）。</li>
                   </ul>