diff --git a/backend/app/helpers/condition.ts b/backend/app/helpers/condition.ts
new file mode 100644
index 0000000..b518293
--- /dev/null
+++ b/backend/app/helpers/condition.ts
@@ -0,0 +1,32 @@
+/**
+ * Quy đổi condition gốc từ ERP về condition chuẩn dùng trong hệ thống.
+ *
+ * Quy tắc:
+ *   NIB, NOB -> NEW
+ *   USEB     -> USED
+ */
+
+/** Các condition gốc từ ERP được phép đồng bộ / lưu trữ. */
+export const SYNCABLE_CONDITIONS = ['NIB', 'NOB', 'USEB'] as const
+
+/**
+ * Convert condition gốc -> condition chuẩn (NEW/USED).
+ * Trả về `null` nếu condition không nằm trong danh sách hỗ trợ (NIB/NOB/USEB).
+ */
+export function convertCondition(condition?: string | null): string | null {
+  const normalized = (condition ?? '').trim().toUpperCase()
+  switch (normalized) {
+    case 'NIB':
+    case 'NOB':
+      return 'NEW'
+    case 'USEB':
+      return 'USED'
+    default:
+      return null
+  }
+}
+
+/** Condition gốc có thuộc danh sách được phép đồng bộ (NIB/NOB/USEB) hay không. */
+export function isSyncableCondition(condition?: string | null): boolean {
+  return convertCondition(condition) !== null
+}
diff --git a/backend/app/services/erp_service.ts b/backend/app/services/erp_service.ts
index d36ad23..e53c70b 100644
--- a/backend/app/services/erp_service.ts
+++ b/backend/app/services/erp_service.ts
@@ -3,6 +3,7 @@ import logger from '@adonisjs/core/services/logger'
 import type Product from '#models/product'
 import type { SupplierPricePoint } from '#models/history'
 import axios from 'axios'
+import { convertCondition } from '#helpers/condition'
 
 interface ErpProductListParams {
   limit?: number
@@ -49,7 +50,7 @@ export default class ErpService {
         limit: 50,
         skip: 0,
         order: 'updatedAt desc',
-        where: { _q: product.sku, condition: product.condition },
+        where: { _q: product.sku, condition: convertCondition(product.condition) },
       },
     }
 
diff --git a/backend/app/services/sync_service.ts b/backend/app/services/sync_service.ts
index b3db5ac..7ebc4ce 100644
--- a/backend/app/services/sync_service.ts
+++ b/backend/app/services/sync_service.ts
@@ -3,6 +3,7 @@ import ProductService from '#services/product_service'
 import LogService from '#services/log_service'
 import ErpService, { type ErpProductItem } from '#services/erp_service'
 import { enqueueProductUpserts } from '#services/queue_service'
+import { convertCondition } from '#helpers/condition'
 
 export interface SyncSummary {
   /** Tổng số bản ghi ERP tự báo cáo (field `total`) — CHỈ tham khảo, không tin cậy. */
@@ -75,7 +76,7 @@ export default class SyncService {
       summary.fetched += page.items.length
 
       // Bỏ qua item rác không có sku (sku rỗng gây trùng unique key -> lỗi insert).
-      const valid = page.items.filter((i) => i.sku && i.sku.trim() !== '')
+      const valid = page.items.filter((i) => i.sku && i.sku.trim() !== '' && i.condition && ['NIB', 'NOB', 'USEB'].includes(i.condition.toUpperCase()))
       summary.skipped += page.items.length - valid.length
 
       if (valid.length > 0) {
diff --git a/backend/package.json b/backend/package.json
index 5d5e176..4469087 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -17,6 +17,7 @@
     "#controllers/*": "./app/controllers/*.js",
     "#models/*": "./app/models/*.js",
     "#services/*": "./app/services/*.js",
+    "#helpers/*": "./app/helpers/*.js",
     "#validators/*": "./app/validators/*.js",
     "#middleware/*": "./app/middleware/*.js",
     "#exceptions/*": "./app/exceptions/*.js",
diff --git a/backend/tsconfig.json b/backend/tsconfig.json
index 0d9f4f2..95d09df 100644
--- a/backend/tsconfig.json
+++ b/backend/tsconfig.json
@@ -7,6 +7,7 @@
       "#controllers/*": ["./app/controllers/*.js"],
       "#models/*": ["./app/models/*.js"],
       "#services/*": ["./app/services/*.js"],
+      "#helpers/*": ["./app/helpers/*.js"],
       "#validators/*": ["./app/validators/*.js"],
       "#middleware/*": ["./app/middleware/*.js"],
       "#exceptions/*": ["./app/exceptions/*.js"],