To design an electrochemical machining (ECM) cathode for machining the mixed rifle with large spiral angle and the experiments are difficult, it takes a long period. Visual C++ was adopted to simulate the process for machining rifle as cathode moves according to the Ballistic equation. The models of 3D working tooth on cathode and the processing environment were built and the arithmetic was established. The length of working tooth was initialized. Having compared above points with design parameter, the parameter of cathode’ working tooth will be modified till it be close to design parameter. At last the result for appropriate parameter of cathode’ working tooth was proposed.