diff --git a/app/Http/Controllers/Admin/PlatformOrderController.php b/app/Http/Controllers/Admin/PlatformOrderController.php
index 43b80ea..8cd4d03 100644
--- a/app/Http/Controllers/Admin/PlatformOrderController.php
+++ b/app/Http/Controllers/Admin/PlatformOrderController.php
@@ -65,6 +65,12 @@ class PlatformOrderController extends Controller
             if ((int) ($defaults['plan_id'] ?? 0) <= 0) {
                 $defaults['plan_id'] = (int) ($siteSubscription->plan_id ?? 0);
             }
+
+            // 续费默认备注：若未显式传 remark，自动补齐“来自订阅：{subscription_no}”用于追溯/检索。
+            if ((string) ($defaults['order_type'] ?? '') === 'renewal' && trim((string) ($defaults['remark'] ?? '')) === '') {
+                $remarkPrefix = (string) config('saasshop.platform_orders.renewal_order_remark_prefix', '来自订阅：');
+                $defaults['remark'] = $remarkPrefix . (string) $siteSubscription->subscription_no;
+            }
         }
 
         return view('admin.platform_orders.form', [
diff --git a/tests/Feature/AdminPlatformOrderCreateRenewalDefaultRemarkFromSubscriptionTest.php b/tests/Feature/AdminPlatformOrderCreateRenewalDefaultRemarkFromSubscriptionTest.php
new file mode 100644
index 0000000..66bb6b9
--- /dev/null
+++ b/tests/Feature/AdminPlatformOrderCreateRenewalDefaultRemarkFromSubscriptionTest.php
@@ -0,0 +1,109 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Models\Merchant;
+use App\Models\Plan;
+use App\Models\SiteSubscription;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminPlatformOrderCreateRenewalDefaultRemarkFromSubscriptionTest extends TestCase
+{
+    use RefreshDatabase;
+
+    protected function loginAsPlatformAdmin(): void
+    {
+        $this->seed();
+
+        $this->post('/admin/login', [
+            'email' => 'platform.admin@demo.local',
+            'password' => 'Platform@123456',
+        ])->assertRedirect('/admin');
+    }
+
+    public function test_create_form_should_autofill_remark_from_subscription_when_renewal_and_remark_not_provided(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $merchant = Merchant::query()->firstOrFail();
+
+        $plan = Plan::query()->create([
+            'code' => 'po_create_renewal_default_remark_plan',
+            'name' => '续费下单默认备注（从订阅补齐）测试套餐',
+            'billing_cycle' => 'monthly',
+            'price' => 10,
+            'list_price' => 10,
+            'status' => 'active',
+            'sort' => 10,
+            'published_at' => now(),
+        ]);
+
+        $sub = SiteSubscription::query()->create([
+            'merchant_id' => $merchant->id,
+            'plan_id' => $plan->id,
+            'status' => 'activated',
+            'source' => 'manual',
+            'subscription_no' => 'SUB_DEFAULT_REMARK_0001',
+            'plan_name' => $plan->name,
+            'billing_cycle' => $plan->billing_cycle,
+            'period_months' => 1,
+            'amount' => 10,
+            'starts_at' => now()->subDay(),
+            'ends_at' => now()->addMonth(),
+            'activated_at' => now()->subDay(),
+        ]);
+
+        $url = '/admin/platform-orders/create?site_subscription_id=' . $sub->id . '&order_type=renewal';
+
+        $res = $this->get($url);
+        $res->assertOk();
+
+        $expectedRemark = config('saasshop.platform_orders.renewal_order_remark_prefix', '来自订阅：') . $sub->subscription_no;
+
+        $res->assertSee('>' . $expectedRemark . '<', false);
+    }
+
+    public function test_create_form_should_not_override_remark_when_remark_is_provided(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $merchant = Merchant::query()->firstOrFail();
+
+        $plan = Plan::query()->create([
+            'code' => 'po_create_renewal_default_remark_override_plan',
+            'name' => '续费下单默认备注不覆盖测试套餐',
+            'billing_cycle' => 'monthly',
+            'price' => 10,
+            'list_price' => 10,
+            'status' => 'active',
+            'sort' => 10,
+            'published_at' => now(),
+        ]);
+
+        $sub = SiteSubscription::query()->create([
+            'merchant_id' => $merchant->id,
+            'plan_id' => $plan->id,
+            'status' => 'activated',
+            'source' => 'manual',
+            'subscription_no' => 'SUB_DEFAULT_REMARK_0002',
+            'plan_name' => $plan->name,
+            'billing_cycle' => $plan->billing_cycle,
+            'period_months' => 1,
+            'amount' => 10,
+            'starts_at' => now()->subDay(),
+            'ends_at' => now()->addMonth(),
+            'activated_at' => now()->subDay(),
+        ]);
+
+        $customRemark = '自定义备注：线下补单';
+        $url = '/admin/platform-orders/create?site_subscription_id=' . $sub->id
+            . '&order_type=renewal'
+            . '&remark=' . urlencode($customRemark);
+
+        $res = $this->get($url);
+        $res->assertOk();
+
+        $res->assertSee('>' . $customRemark . '<', false);
+    }
+}