A high precision sun tracking servo closed-loop control system is designed using STM32F429 as main controller

and control precision is improved by combining solar motion trajectory with photoelectric tracking. By using global positioning system（ GPS） module to obtain the time and longitude and latitude information needed by astronomical algorithm

the altitude angle and azimuth angle of the sun can be calculated at present time

but the installation error can not be eliminated. The sun image is collected by camera

the center of mass is calculated

and the astronomical zero point is found

so as to eliminate the installation error of the system. At the same time

the error value is stored into electrically erasable programmable read-only memory（ EEPROM） timely. When the image can not be tracked due to weather and other reasons

the system uses a method combines solar motion trajectory with storage error to track the sun. Experiments show that the servo closed-loop tracking system can achieve control procision less than 0. 1 %. It is of great significance in improving the utilization rate of solar energy in civil defense

military and other aspects.