The invention discloses a device and a system for implementing a multi-carrier high speed downlink packet access service, thereby accomplishing multi-carrier high speed downlink packet access service transmission by means of multi-carrier high speed downlink packet processing devices provided in a base station and a user equipment in the system and managing high speed downlink packets corresponding to the carriers separately by means of hybrid automatic repeat request modules corresponding to the carriers. The invention further discloses a method for implementing a multi-carrier high speed downlink packet access service, thereby allocating a separate transmitting hybrid automatic repeat request process and corresponding receiving hybrid automatic repeat request process for each carrier to accomplish transmission and receiving of high speed downlink packet access data. With the invention, the downlink data transmission rate in a radio mobile communication system supporting multiple carriers can be improved.