The principle of coupler with planetary mechanism was elaborated. The coupler can decide the HEV driving mode through a set of clutches engaging and disengaging. The rotation and torque composition of coupler was analyzed through the means of virtual level. The fuzzy algorithm was proposed to control the clutches for desired transient and smooth performance. The acceleration pedal travel and its change rate were used as input, and the output were clutches initial pressure and the change rate of engaging pressure. The simulation model of the coupler with planetary mechanism was established finally. The simulation results showed that this control strategy could meet the driver operating demands, increase HEV speed and switch driving mode smoothly under different driving conditions. 