diff --git a/src/CMSMicroservice.Application/UserCartsCQ/Commands/CreateNewUserCarts/CreateNewUserCartsCommandHandler.cs b/src/CMSMicroservice.Application/UserCartsCQ/Commands/CreateNewUserCarts/CreateNewUserCartsCommandHandler.cs
index 0cb9f48..702237f 100644
--- a/src/CMSMicroservice.Application/UserCartsCQ/Commands/CreateNewUserCarts/CreateNewUserCartsCommandHandler.cs
+++ b/src/CMSMicroservice.Application/UserCartsCQ/Commands/CreateNewUserCarts/CreateNewUserCartsCommandHandler.cs
@@ -13,6 +13,16 @@ public class CreateNewUserCartsCommandHandler : IRequestHandler<CreateNewUserCar
         CancellationToken cancellationToken)
     {
         var entity = request.Adapt<UserCarts>();
+        var existingUserCart = await _context.UserCartss
+            .FirstOrDefaultAsync(x => x.UserId == entity.UserId && x.ProductId == entity.ProductId && !x.IsDeleted, cancellationToken);
+        if (existingUserCart != null)
+        {
+            existingUserCart.Count += entity.Count;
+            _context.UserCartss.Update(existingUserCart);
+            existingUserCart.AddDomainEvent(new UpdateUserCartsEvent(existingUserCart));
+            await _context.SaveChangesAsync(cancellationToken);
+            return existingUserCart.Adapt<CreateNewUserCartsResponseDto>();
+        }
         await _context.UserCartss.AddAsync(entity, cancellationToken);
         entity.AddDomainEvent(new CreateNewUserCartsEvent(entity));
         await _context.SaveChangesAsync(cancellationToken);