Abstract: The optimal control of Proton Exchange Membrane Fuel Cell（PEMFC）stacks need accurate model and parameters. The mechanism model of stack output voltage is established in this paper based on semi-empirical model,the empirical formula of stack output voltage characteristics,electrochemical principle and thermodynamic principle. Then,the linear regression method of least square method is utilized to identify the model’s key parameters. At last,the error analyses of simulation results indicate that the accuracy of stack parameter identification reaches the control requirements,which verifies the effectiveness and feasibility of the proposed method.