the dark current noise existing in the ccd of the astronomical observation camera has a serious influence on its working performance, reducing the working temperature of ccd can suppress the influence of dark current effectively. by analyzing the relationship between the ccd chip and the dark current noise, the optimum working temperature of the red band ccd focal plane is identified as -75°c. according to the refrigeration temperature, a cooling control system for focal plane based on a thermoelectric cooler (tec) was designed. it is required that the system can achieve high precision temperature control for the target. in the cooling control system, the 80c32 microcontroller was used as its systematic core processor. the advanced pid control algorithm is adopted to control the temperature of the top end of tec. the bottom end of the tec setting a constant value according to the target temperature used to assist the upper tec to control the temperature. the experimental results show that the cooling system satisfies the requirements of the focal plane for the astronomical observation camera, it can reach the working temperature of -75°c and the accuracy of ±2°c. © 2017 spie.