Abstract: The deformation of large size, multi-channel and highly integrated microwave muti-chip modules during the micro-assembly process is studied in this paper. The results show that the shell bottom is concave in direction of the module cavity and the maximum deformation is equivalent to 6.9% of the thickness of shell bottom plate after the substrate is soldered to the shell; after the module is sealed, the concave degree of the shell bottom facing the cavity is reduced and maximum deformation is equivalent to 3.0% of the thickness of the shell bottom plate; after milling the bottom surface, the flatness of the shell tends to be better and the maximum deformation is not more than 1.2% of the thickness of the shell bottom plate, which meets the requirements of module installation and efficient heat dissipation; after the mechanical opening and secondary sealing of the module, the deformation of the bottom surface of the shell changes from concave towards the cavity to convex towards the bottom and the maximum deformation is less than 1.5% of the thickness of the shell bottom plate. The module installation and efficient heat dissipation requirements can still be guaranteed without taking measures.