In light of the current research on Battery Management System （BMS） circuit boards for electric vehicles， which only takes into account the temperature field and heat dissipation effects of individual functional module but lacks consideration of the interdependence and cooperative effects under the temperature and force fields among multiple functional modules of the BMS， a certain commercial BMS circuit board is taken as the research object， the software ANSYS is used to construct a thermal-stress coupling numerical simulation analysis model that characterizes the synergistic action of multiple BMS modules， and the effectiveness of the model is verified. On this basis， a numerical simulation study was carried out on the temperature field and thermal deformation behavior of each functional module of the BMS circuit board. The results show that the temperature distribution of the BMS circuit board is uneven， and the maximum temperature difference reaches 20.5 ℃. The balancing module generates heat， and the temperature reaches 54.4 ℃， which causes thermal expansion and deformation of circuit board components. At the same time， thermal stress concentration occurs at the chip resistors on the edges of the balancing module and the power supply module due to the circuit board constraint， which causes the balancing module and the power supply module of the BMS to produce protruding and warping deformation. The Z-axis thermal deformation increases with the temperature rising， and the maximum deformation amount reaches 9.5 μm. Therefore， the heat dissipation optimization design should be carried out for the heat-generating modules on the BMS circuit board.