The gas measurement and application sensor based on semiconductor laser double mode feature uses target gas to generate laser with certain wave length to absorb feature gas intensity measurement, alsousing target gas as the reference signal to offset other consumption and waving effect for the light transmission feature with certain wave length generated by the same laser. The core of the gas sensor is a semiconductor laser and a photoelectric detector, suitable for all kinds of gas light path being simple, small and integrated. It is of good versatility.