Abstract: In the multi-gas detection process, the spectrum line modulation is used to achieve the best effect of detection, which is an important part of spectral analysis testing technique for coal mine disaster gas. According to the measurement of disaster gas concentration underground, it can meet the multi-gas detection requirements of spectrum lines, and each line can achieve optimal detection, thus these methods can greatly improve the test sensitivity of multi-gas concentration for mine-used spectral analysis equipment based on TDLAS technology.