Abstract: The gas detection apparatus is developed by using tunable diode laser absorption spectrum detection technique (TDLAS), it is spread in large area in the field of coal mine disaster gas detection area. The calibration cycle of laser gas sensor is long, it is not affected by water vapor, dust and other gas interference, and it has fast response speed and low measurement error, these characteristics are incomparable for other type sensors. The design of laser gas sensor is discussed in detail based on TDLAS technology, to improve the advantage of tunable diode laser absorption spectroscopy in coal mine disaster gas detection process.