Tunable diode laser absorption spectroscopy (TDLAS) is a non-invasive spectral detection technology with high selectivity, high response and high resolution. According to the principle of molecular spectral absorption, the change in target gas temperature will affect the change of molecular absorption line strength and then affect the accuracy of gas concentration inversion. In order to improve the accuracy and authenticity of gas concentration measurements in high-temperature atmospheres, carbon monoxide (CO), a common gas in industrial processes, was selected as the target gas. Experiments were designed to detect the gas spectra in multiple temperature regions (from 14 to 1 100 ℃) based on wavelength modulation technique, compared with spectral parameters in the HITRAN database, and the results were calibrated and analyzed. At the same time, the influence of different materials of sapphire window pieces was analyzed in terms of parameters such as the linearity of the detection signal. A cooling gradient measurement was selected as the temperature control sequence for the high-temperature experiment by analysing the data from the temperature rise and fall experiments. Through the high-temperature experiment with a standard concentration of CO, it was found that the second harmonic (2f) amplitude and absorption line intensity had a consistent decreasing trend with increasing temperature, by the theoretical equation of variation law. After analysis, the corrected 2f amplitude and temperature show a non-correlation and a correction for the effect of temperature on spectral detection is achieved. The shortcomings of the correction formula and the proposed improvement method are remedied, and the accuracy of the 2f amplitude correction at variable temperatures is verified. This study provides a reference for the practical application of spectral detection technology in the measurement process of high-temperature environments, especially for the dynamic evaluation of combustion efficiency in high-precision industrial furnaces, which is of great importance.