Abstract: For commonly used wet multi-plate clutch in automatic transmission(AT), completed the optimized design of the clutch using fuzzy theory and main objective method with optimization toolbox of MATLAB. According to clutch design formula, the optimal design mathematic model was set choosing average energy loss in sliding friction surface at the end time of bonding and the max power loss per area as the optimized object and turning clutch torque capacity calculated as a whole into a constraint condition. Also the dynamics implementation simulation model with multi-disciplinary dynamic simulation software platform Simulation X was set. Through the model, the change of the relative thermal index after optimized could be truly reflected,and the operation characters of clutch are heightened.