This paper presents an experimental study on engine control strategy during gear shifting for a Unimog U4000 equipped with an automated mechanical transmission (AMT) based on the controller area network (CAN) bus. First, an integrated powertrain control system based on the CAN bus is introduced. Second, the ideal AMT gear shifting process is described, and the engine control strategy during gear shifting is proposed. Then, the communication information for the engine control unit (ECU) and transmission control unit (TCU) during gear shifting is determined based on the SAE J1939 protocol. Finally, effectiveness is verified by the experimental results. The experimental results show that: engine control during gear shifting based on the CAN bus can meet the requirement for real-time operation; the engine control strategy presented in this paper during gear shifting can achieve good shift quality with shorter shifting time and less vehicle speed loss.