To address the detection needs of the infrared thermal imaging system，an infrared surface-source blackbody was designedwhich was composed of purple-copper radiant surface，thermoelectric cooler and cooling fin，etc.The high-precision acquisition of the environment temperature and the radiant surface temperature was realized by using the platinum thermistor and 24 bit AD sampling. To solve the problems in the blackbody of big time constant，response lag，persistent disturbance of the environment temperature，a fuzzy PID controller was designed. The control parameters of it were set in real time according to the error and the error variation rate.The goals of small overshoot，rapid response speed and high steady-precision were realized. It is proved by experiments and tests that the temperature control precision is ±0.03 ℃，and the response time is less than 180 s，which meet the design requirements.