This paper designed a high-precision temperature-control circuit system based on TEC.Introduction was made to the selectionmethod of TEC,realizing a hardware circuit based on singleˉchip and using PID software control algorithm to optimize parameters.In experiment?choosing the higher thermal load copper block as the temperature control object to do the test verification.The result shows when the ambient temperature is 23℃,the temperature control range of the copper block is (10~40℃).The temperature control precision can be up to 0.01℃.