Abstract: For problems of being easily affected by environment, low detection decision and poor stability in traditional methane detection system, a distributed multi-point laser methane detection system was designed based on tunable diode laser absorption spectroscopy technology and space division multiplexing technology. The system adopts distributed feedback semiconductor laser with wavelength of 1 653.7 nm as light source, uses ratio of the second harmonic and the first harmonic gotten by harmonic detection to invert methane concentration, and employs 1/8 beam splitter and reference air chamber to realize real-time multi-point methane concentration detection. The system has been tested in laboratory. The test results show that the system has high accuracy and good stability, can realize monitoring points within 10 km effectively covered, and measurement error is less than 2% when methane concentration is 2.00%-85.0%.