Aiming the vehicle ride performance, the process of driving mode-switch for a heavy hybrid power system and parameter changes among the engine, motor, clutch and transmission during the Mode-Switch process between Motor and Engine Driving were analyzed. The coordinated torque control strategy was established for Mode-Switch between motor and engine driving. The heavy hybrid electric vehicle simulation model was developed based on the strategy. The performance for the mode-switch process between motor and engine driving was simulated and analyzed. The results show that introducing the coordinated control strategy reduces the torque fluctuation during the driving-mode-switch process and improves the vehicle drivability.