Detection principle of methane detection by non-dispersive infrared（NDIR） spectroscopy is introduced.The gas concentration detection system based on STM32 embedded processor is designed

the gas concentration is calculated by the least square method

and the gas concentration correction method based on temperature compensation is proposed.The RS—485 bus is used to realize the communication between the controller and the upper computer

and the datas between the gas concentration detection system and the ground monitoring center are transmitted.This detection system has high measuring precision and stable performance

and the measurement error is less than 2.2 %

which has been applied in the detection of coal mine gas.