The dressing quality of forming grinding wheel directly affects the tooth profile accuracy and surface quality of the screw rotor. Based on the meshing theory,the mathematical model of grinding screw rotor was established and the contact line equation between forming grinding wheel and the rotor was deduced.In view of the rotor’s end-surface tooth for discrete points,the forming wheel edge shape was calculated with the bridging use of cubic spline interpolation method,chasing method and MATLAB built-in fsolve function.According to the working principle of CNC grinding wheel dresser,a scheme of the grinding wheel dressing was designed on the calculation results.A simplified method of CNC programming was put forward after studying the changing rules between grinding wheel’s cross-sectional profile and center distance. This method is simple, reliable and high-precision,especially suitable for the complex curves.