Abstract：In this paper, we analyze production rule of gaseous combustion products in fires, and put forward CO2 as parameter of fire detection. Through accurate monitoring of CO2 concentration in the environment, the aircraft fire detection has been realized. Considering the particularity of environmental condition on aircraft, NDIR（Non-Dispersion Infrared）is used to resolve the challenge of temperature compensation in aircraft fire detection. According to the relationship among the measured voltage of aircraft fire detector, environment temperature and reference voltage, temperature compensating model for aircraft fire detector is established based on partial least squares (PLS) approach. And model for CO2 concentration calculating is built by using partial least squares (PLS) method, which is based on correlation between measured voltage of aircraft fire detector and CO2 concentration. With the calculated concentration of CO2, an alarm algorithm for aircraft fire detector is presented then, which provides a new fire detection method for aircraft.