Based on the need of spaceflight design, a driver of rotating parts of a space-borne spectrometer was designed to accurately control the locating of the three motors. Motor’s accurate positioning is completed by resetting and fixed steps of micro switch. Fine adjustment of driving current is completed by using PWM mode. A platform was built and repeated tests were given to the design. The result showed that the system has high reliability and stability and can fulfill the requirements of accurate locating to make sure that the motors can finish the calibration according to the arrangement.