Abstract: In infrared absorption detection of methane, the key to improve detecting precision is to compensate the errors. Various differential absorption techniques are usually adopted to compensate the errors, which reduce different kinds of interferences. On the basis of infrared differential detection, a dual-wavelength difference methane sensor was designed. A rotating filter was used to control the filtering and passing through of the light, which made the detecting light and reference light pass through the optical path in a time-sharing way. The sensor structure of single-source single-light-path and single-detector was implemented, eliminating the errors caused by the source power fluctuations, the light-path loss and the detector instability. The experiments show that the sensor has high measurement precision: in the concentration range of 0~6%, the maximum relative error is less than 1%.