Excessively high temperature can greatly increase the thermal noise of TDI CCD, which will reduce the camera's image quality significantly, so thermal control methods must be taken to decrease the temperature of TDI CCD focal plane. One high-speed TDI CCD circuit, which had a difficulty in heat dissipation because of high power density, was discussed in detail. Limited by the mass and power consumption, traditional radiant cooling panel method couldn’t be used. Based on the stronger temperature adaptability, the method of reducing the temperature of camera and using the large heat capacity character of electricity box was taken on the focal plane. Through the camera’s thermal balance test, thermal control effect of the method was verified, and the optimization scheme was presented. The results show that, under high temperature cases, the maximum temperature of TDI CCD is 30℃，about 10℃ lower than nothing thermal control method was taken, and the method can satisfy TDI CCD’s requirements well.