Abstract: In order to simulate the direction change of the solar light in space, a computer control system of the solar simulator for high precision solar sensors is developed. The photoelectric isolation card of the computer control system outputs digital signals directly to turn on or off the solar simulator light source by the power drive and the soft start circuit, to control the step motor’s direction and speed by software, to obtain the current angle values by a high precision photoelectric encoder, then to feed back to computer to complete a closed-loop system. The experiment results show the rotational errors for the elevation angle and the azimuth angle are both less than 0.02°, which can satisfy the high precision requirements of solar sensors.