Based on principle of the bidirectional reflectance distribution function(BROF) and theory of harmonic detection about remote sensing system, we design and build a gas pipeline leak detection system of laser remote sensing. This platform detect distance is 120 m. The concentration of 0.308％ on the natural gas simulation of remote sensing can realized the air trace gas detection of methance. The minimum detection sensitivity of the system is about 29.75 ×10-6 m. At the same time we studied the efficiency ρtotof various reflection scattering effect on the experiment. The feasibility of the new calibration method for the concentration is proposed and experimentally verificated. The experimental results can using in the real detection.