According to the principle of electric spark processing, a motor control system for electric spark sharpening machine tools is designed by using single chip microcomputer. The hardware circuits including sampling circuit, variable frequency speed regulation circuit of sharpening motor and sharpening speed control circuit, and system software design are introduced. The function and performance of the control system are tested. The test results show that the motor control system can meet the requirements of the sharpening machine tools for the grinding of superhard materials.