In order to obtain better anti-blocking device on no-till planter, a finite element analysis on gap disc with ANSYS was conducted. Through element type selecting and material properties setting, ANSYS could transfer gap disc image into mesh size and generate a finite element model, in which loadings consisted of straw-cutting resistance and soil-penetrating resistance. Then the gap disc model was calculated, a series figure of different components of stress was obtained. Theoretical basis of further modification and optimization for gap disc was given.