diff --git a/Service/DeviceService.cs b/Service/DeviceService.cs
index dbb42bc..d70e435 100644
--- a/Service/DeviceService.cs
+++ b/Service/DeviceService.cs
@@ -64,8 +64,8 @@ namespace LY.App.Service
         public async Task<ApiResult> Add(AddDevice input)
         {
             var entity = input.Adapt<DeviceEntity>();
-            var exists = await _db.Queryable<DeviceEntity>().FirstAsync(s => s.DeviceSN == entity.DeviceSN);
-            if (exists!= null)
+            var exists = await _db.Queryable<DeviceEntity>().FirstAsync(s => s.DeviceSN == entity.DeviceSN && s.IsDeleted == false);
+            if (exists != null)
             {
                 return new ApiResult()
                 {