Coal is the most important energy mineral in China, and methane gas is the main harmful gas in the mine production process, which may causes miners to be poisoned and even causes major safety accidents such as fire and gas explosion, which seriously threatens the life safety of coal miners and affects the mining progress. In order to prevent the occurrence of safety accidents caused by hazardous gases, the real-time monitoring of harmful gases in the mine is an important measurement to ensure the safety of mine production. Only by monitoring and detecting the concentrations of these harmful gases in a timely and accurate manner can problems be found early and corresponding measures taken.At present, as a new type of high-sensitivity, high-resolution, anti-electromagnetic interference sensor, tunable diode laser is widely used in various fields, and is an effective means to detect gases. In this paper, the Tunable Diode Laser Absorption Spectroscopy (TDLAS) is used. Based on the Lambert-Beale law, the relationship between gas concentration and signal intensity is analyzed. Based on TDLAS, a multi-component gas long-distance sensing system was designed to carry out remote real-time monitoring of harmful gases in the mine, so as to realize the real-time concentration monitoring of multiple gases in the mine environment from kilometers away.In this paper, four gases that may occur in the mine were calibrated, namely carbon monoxide gas (CO), carbon dioxide gas (CO₂), methane gas (CH₄) and ethylene gas (C₂H₄). The calibration curves of the four gases and lower detection limits were obtained. The coefficients of determination R² were all greater than 0.99, indicating that the linear fittings were accurate. The lower detection limit for each gas can be less than 0.01%. Especially for methane gas , the main component of harmful gas, the calibrated linear correlation coefficient R reaches 0.995 54, and the detection limit is as lower as 2.2×10^-6. The stability of the measurement is 0.137%. For the remaining three selected gases, the carbon monoxide gas reached the lower detection limit of 27.1 ×10^-6, and the stability of the measurement was 0.402%; the carbon dioxide gas reached the lower detection limit of 23.2×10^-6, and the stabilityof the measurement was 0.365%. The ethylene gas reached the lower detection limit of 80.7×10^-6, and the stabilityof the measurement was 0.291%.After the calibration in lab, the gas detection equipment was applied in coal mine. The long-term monitoring results are consistent with the the gas detection system owned by the mine. By random sampling of the gases, detection results are compared with the third-party test results and the difference between the two is within 5%. The multi-component gas monitoring system has the advantages of high accuracy, low monitoring limit and good stability, which can provide reliable data support for mine gas safety and has a promising application in the mining industry.