Underground space counter-reflective methane sensor based on Tunable Diode Laser Absorption Spectroscopy (TD-LAS) development, using 1653.7nm laser methane gas characteristics of the“fingerprint spectrum” absorption detection, resistance to interference with water vapor or other gases, the sensor adopts counter-reflective optical circuit design, simple structure, stability and reliability; selection of low-temperature performance excellent laser and photodetector devices and the use of wide temperature compensation correction algorithm, strong environmental applicability; the product as the core component of the combustible gas monitor for underground space and other harsh workplace gas leak detection and alarm. It adopts laser and photodetector devices with excellent low-temperature performance and wide-temperature temperature compensation correction algorithm, which is highly applicable to the environment; as the core component of the combustible gas monitor, the product is used for detecting and alarming gas leakage in underground spaces and other harsh workplaces.