For the interlocking masonry structure stacked by cravat shaped brick and mortar, regular tessellation theory and homogenization theory are used to analyze the axial tensile deformation and stress-strain curve. The relationship between effective modulus in elastic phase and Poisson’s ratio and strain energy in inelastic phase and geometry of brick and property of interface is constituted through the analysis. Based on obtained curve and relationship, the strengthening mechanism and realizing way of the masonry structure are discussed. It is found that neighboring bricks sliding are impeded by the interlock in overlap region due to the inclined interface and friction. The practical meaning is the tensile properties of masonry structure can be usefully improved by the introduced declining interface.