A temperature control system with high stability and precision is designed by using STM32 MCU to control TEC of semiconductor refrigerator.The whole temperature control system mainly includes:STM32 MUC minimum system,temperature control module,temperature control serial host computer,PID algorithm,TEC and so on.By improving the temperature control module,the switching loss can be reduced and the working efficiency and reliability of the circuit can be improved.At the same time,the integral separation PID algorithm is improved to variable speed integral PID algorithm to achieve stable and high precision temperature control.