The invention relates to a dual-wavelength difference methane concentration sensor. The dual-wavelength difference methane concentration sensor comprises a light source, a light processing module, a signal processing module and a signal analyzing module, wherein the light source is used for sending out light signals. The light processing module comprises a photoelectric detector and is used for filtering the light signals sent by the light source to enable a set of the light signals with a first wavelength and a set of the light signals with a second wavelength to pass through, periodically enabling the two sets of the light signals to pass through gas to be detected respectively to be transmitted to the photoelectric detector and converting the light signals into electric signals by the photoelectric detector. The signal processing module is used for filtering and amplifying the electric signals output by the light processing module. The signal analyzing module is used for analyzing the electric signals output by the signal processing module to obtain the concentration of methane.