Abstract: Based on the linear elastic plate theory, the rigidity of a concave template of a right angle trapezoid cross section made of homogeneous, continuous and isotropic material with a circular hole is calculated. At first, a mechanical and mathematical calculation model is built. Secondly, the third order variable coefficient differential equation expressed in deflection is obtained with boundary conditions. And then, the deflection is obtained, as well as the rigidity. Finally, an application example is given.