This paper shows a model based design method for PHEV hydraulic module. Firstly, system scheme is designed due to system function requirements and is verified preliminarily by function level modeling & simulation. Secondly, detailed models of hydraulic parts (hydraulic valves, actuators, etc…) are set up. Some part structure parameters are designed according to detailed model simulation. Thirdly, detailed hydraulic model is set up by parts model integration, the system design is further verified by completed model simulation. After prototype production, simulation result is compared with prototype test result and two results have good correlation. So this model based design method for PHEV hydraulic module is practical and has good effect on development period & cost reduction.