55.42％。This paper analyzed and confirmed the whole car modes of driving, modes conversion transient algorithm, planetary system kinematics limited model for a certain parallel-serial hybrid electric vehicle configuration, and proposed based-power-track control strategy. Combining Cruise with Matlab, we carried out the combination simulation under Udc-auto cycling run condition. The simulation result showed that mode conversions are stable, and tracking pre-defined car velocity effect is good. The engine can be controlled to work at the vicinity of its optimizing curve under accelerating condition of medium and high velocity of vehicle. The control strategy and algorithm are valid. Compared with conventional vehicle, HEV control strategy can realize that the decreasing ratio of fuel consumption reaches 55.42% under the same cycle run condition.