Abstract: The three dimensional microwave multichip modules (3D MMCMs) are key parts of new generation solid state active phased array conformal antenna and smart skin. In this paper, the miniaturized, low insertion loss and high relia bility vertical microwave interconnection techniques which are most important for realizing 3D MMCMs are described in de tail. The solderless vertical microwave interconnection with fuzz button structure and the vertical interconnection microwave transmission structure with epoxy resin encapsulation were simulated and optimized respectively. The corresponding processes were developed. The miniaturized, wide operation frequency range, low insert loss and high reliable vertical microwave inter connection for 3D MMCMs was realized successfully.