Abstract Tunable diode laser absorption spectroscopy (TDLAS) is often used to detect gas concentrations in many fields. But because of the ambient temperature changes, the measured harmonic signals’ amplitudes are affected and lead to the monitoring errors. The impact of the temperature on the measurement as well as the temperature compensation method is emphasized. So in order to modify the inversion results and adapt industrial measurement, combustion diagnostics, the numerical fitting empirical modified equation and theoretical modified equation from HITRAN database are discussed and compared in this paper. In experiment, the 21% Oxygen as the safety monitoring gas and absorption wavelength at 760.77 nm are employed. Meanwhile, the first harmonic signals are also used to decrease the laser intensity’s fluctuations. We obtained the unmodified and modified results with the tube furnace in the field of different temperature: 300K~900K (interval 50K). The experimental results show that these two modified methods have some effective affects on the temperature changes and can be applied to gas monitoring correction to improve the accuracy and feasibility of the TDLAS technology. In addition, it also provides evidence for the real-time gas monitoring in the application of combustion diagnosis.