Abstract: The slippage stress of micro-interface was analyzed by the microstructure and two-scale interface characteristics in two-scale interface multiphase ceramics. First, the micro-average stress field of the two-scale interface multiphase ceramics was calculated based on the macroscopic, mesoscopic and nanoscopic elastic properties of multiphase ceramics. Interfacial strain model was proposed on the basis of continuity of displacement and stress in nano-interface, and then, the displacement function of fiber and matrix in the vicinity of nano-interface was calculated. Considering the proportional relationship between interfacial strain and interfacial elastic modulus, shear stress under the conditions of external load transfer to the micro-interface was calculated according to nano-interface properties and fiber distribution. At last, combined with yield shear stress of multiphase ceramics which was determined by the indentation test of multiphase ceramics, the theoretical formula of micro-interface slippage stress of multiphase ceramics was obtained. The quantitative results show that the smaller the interfacial elastic modulus and interfacial Poisson's ratio, the easier the interface is to slip, and the easier the plastic deformation of multiphase ceramics.