According to the problems that the change of temperature can affect the observation results of sun photometer and the temperature correction coefficient is inconvenient to obtain, a temperature control system of automatic sun photometer based on thermo-electric cooler (TEC) was designed. The whole design, especially the temperature control system design, of automatic sun photometer was introduced, and the effect of temperature on detector response was analyzed. The performance of the automatic sun photometer was tested in the field. In Hefei area, China, the automatic sun photometer was compared with the commercial instrument CE318, and the results show that the aerosol optical depth retrieved by the automatic sun photometer is consistent with the corrected result of CE318, with the difference less than 0.01. The long-term test results in Dunhuang area show that the temperature control system of the automatic sun photometer can be kept within (25 ± 0.2) ℃ for long-term field observation with large temperature changes, which verifies the effectiveness and reliability of the system design.