In order to suppress the serious influences of environmental temperature and humidity on the measurement accuracy of the nondispersive infrared ( NDIR) CO2 gas sensor, the low humidity and constant temperature control modules were designed from the perspective of hardware compensation. The gas-drying tube constructed by the polyvinylidene fluoride ( PVDF) hydrophobic filter membrane and 3A molecular sieve is used to reduce the humidity of gas chamber, and the proportion integration differentiation (PID) algorithm is applied to adjust the power of the heating plate wrapped the outside of optical gas chamber to achieve a constant temperature effect. The influence of humidity and temperature on the accuracy of gas concentration measurement is studied. At the same time, the anti-interference design of the low-humidity and constant-temperature is tested and verified. Experimental results show that the low humidity control module based on the gas-drying tube can reduce the humidity of CO2 gas to about 8%, and the constant temperature control module can stabilize the temperature of the gas chamber at 40 ℃ . In a complex temperature and humidity environment, the average relative error of the concentration measurement of CO2 gas sensor including the anti-temperature and humidity interference design is 8. 38% within the gas concentration range of 0 ~ 2 000×10 -6 , which significantly reduces the temperature and humidity drift of the detection system. The research results have certain reference value for the development of high-performance NDIR gas sensors.