Abstract: To deal with the Engine start issue in single-axle parallel hybrid vehicles, the five-stage control strategy based on shifting process without disengaging clutch is designed and the control algorithm of Bang-Bang-PID and feed-forward PID control for motor speed control is presented. The control strategy is applied to vehicle control unit (VCU) by rapid prototyping methods. Finally the control strategy is validated by experiment through the real hybrid electric bus. The results show that control method can improve the switch performance and enhance the vehicle drivability, which meets the requirements of engine start.