Abstract: In the packaging structure of microsystems, package failure caused by thermal stress is an important reason affecting its reliability. At this stage, a large number of reliability tests are usually required to verify the reliability of the packaging structure process. The emergence of finite element simulation methods provides a simpler and more accurate way for such problems. In this study, the finite element simulation of the microsystem package structure was carried out by ANSYS Workbench software, and the influence of the grid type, grid density and number of cycles of the Ball Grid Array(BGA) solder joints in the package structure on the simulation results was systematically explored. The research results provide important reference and theoretical guidance for improving the finite element simulation efficiency and optimal design of microsystem packaging structures, and also provide useful ideas for further research on the reliability of microsystem packaging structures under complex working conditions.