Methane is a major constituent of natural gas,mine atmospheres,and gas fuels.On account of its inflammable and explosive characteristic,gas explosion is a big problem in natural gas station and mining industry. Tunable diode laser absorption spectroscopy(TDLAS)is a gas detection technique provided with high sensitivity,high precision,high selectivity,and rapid responsibility,which has large development in recent years. Wavelength modulation spectroscopy(WMS)is an important technique of TDLAS. In this paper,the WMS technique have been used to detect the methane,and prove the intensity of 2f signals is in direct proportion to the methane concentration in the concentration range between 0.04% and 10%. This WMS technique can be used in methane detection in industrial occasion,and based on these an instrument of methane detection can easily be integrated.