Combining Raman fiber amplification technique with wavelength modulation technique for the first time, the power of near-infrared laser is amplified by Raman optical fiber amplifier, and the laser amplified is used for the long-distance remote detection of nature gas pipeline leak. Raman fiber amplifier performances are tested at 1650 nm range. It’s found that when the output power of Raman fiber amplifier is Pout, f and Pout meet certain linear relationship in order to ensure non-deformation of the output signal. Based on it, 500 m long distance laser remote sensing detection is realized. It lays the foundation for research of laser remote sensing technology of natural gas leakage on airborne platform.