The heat transfer between the IGBT of motor controller and radiator wall, the heat convection between cooling medium and wall radiator,the heat stress,deformation and other factors were considered, the calculation model that could be used to analyze the fluidsolid coupled heat transfer was established based on liquid cooling for motor controller of electric vehicle. The influence of the radiator structure on the heat transfer performance, thermal stress and deformation of the radiator under different working conditions was comprehensively analyzed by using the heat dissipation model. The calculation results show that the heat transfer effect and the lower temperature stress can be obtained by optimizing the structural parameters of the radiator fin, and the radiator structure has better process performance.