A novel parallel hybrid powertrain was proposed. The PX type single-loop system was adopted. It could effectively avoid the CVT’s torque and power capacity. By serially connection to 2-speed gearbox,The PX type single-loop system ratio spread was enlarged. For regenerative braking mode,the power flow reversibility of the PX single loop system was verified.The electric motor was used to realize pure electric drive and recovery braking energy. At high speed and heavy load,the vehicle was driven simultaneously by the engine and the motor. The bond graph model of the powertrain was established,and the state equation of the system was given. Based on MATLAB/Simulink,the vehicle simulation model was established,and the highway portion of the US06 drive cycle was selected to simulate the powertrain. The simulation results show that: through mode switch,engine operates in high efficiency areas,and the actual speed of the vehicle can well follow the driving cycle. At the same time,the battery state of charge is ensured in the expected range before and after the simulation.