This paper presents a method using tunable diode laser spectroscopy and wavelength modulation technology to realize the
research of multi-channel distributed fiber optic gas monitoring system. The sensor probe consist of gas cell and fiber optic
without any circuit, therefore this system can realize the prediction and forewarning of gas concentration of non-electrical,
long-distant, on-line and distributed. The experiment shows four channels fiber optic gas monitoring system is not
influenced by variation of fiber length, and the system can get a correct detection of methane concentration value.