A certain CNC shearing machine was taken as the research object.A commonly used Novartis Surrey shear stress formula was introduced， then threedimensional shear model was established by using SolidWorks, the simulation of cutting process was analyzed by Deform3D finite element analysis software. The method of strain electrical measurement was used to test the shear stress of the brake type shearing machine. It is found that the simulation result and the experiment test are basically same; also, the simulation value is similar with the calculated result of Novartis Surrey formula. It provides basis that finite element method is feasible to solve problems.