A blanking method which can punch the sheet metal without burr is presented, this method is divided into two stages: preloading deformation and blanking. And the FEM software DEFORM-2D is used to simulate the blanking process of burr-free of stainless steel AISI304. By changing the size of relative clearance, analyzing the quality of cross-section and blanking process. The result shows that the clearance has an effect on blanking force and the length of shear zone. which provides the certain fundamental for predicting the defects of blanking pieces and designing the molds. And this method has an important application value in manufacturing engineering.