According to the structure of gas cavity and the properties of optical components， an accurate circuit control method of constant temperature and stability control box is designed， and the high-precision stability control of multi-temperature state inside the box is realized.The temperature control system can be used to study the variation of gas temperature and gas absorption spectrum parameters， and improve the detection accuracy of gas concentration.The hardware circuit system including high-precision constant-current source， two-channel temperature sampling module and conditioning circuit， A/D analog-digital conversion circuit and semiconductor refrigerator control module is designed.The corresponding system software is developed to ensure the uniformity of the temperature of the optical cavity.According to the actual temperature control box parameters， with the proportional integral differential control algorithm as the core， the temperature change inside the optical cavity is precisely controlled， realizing the optimal temperature change control fluctuation inside the temperature control box is ±0.009 ℃ and the standard deviation is lower than 0.006 ℃.Temperature control experiments are carried out under seven temperature states of 16 ℃， 20 ℃， 24 ℃， 28 ℃， 32 ℃， 36 ℃ and 40 ℃ respectively using CO₂ standard gas with a concentration of 2.00%. The stability of the temperature control system is verified through the measurement results.