Retrieving the profile of PM2.5 (particulate matter less than 2.5 μm in diameter) mass concentration can not only estimate column mass concentration of pollutants, but also follow pollutants diffusion rule in space, so as to provide scientific support for the prevention and control of atmospheric pollution. Suppose that the type and component of aerosol remain unchanged in the period of one PM2.5 mass concentration detection in the boundary layer, by using the proportional relation between the aerosol extinction coefficient and PM2.5 mass concentration at ground, the profile of PM2.5 mass concentration can be obtained from the profile of aerosol extinction coefficient which is retrieved by the lidar system. Two cases of PM2.5 mass concentration and the characteristic change with altitude and time are analyzed, and the 82 nights data measured from March 2014 to February 2105 are averaged by season. The average profile of seasonal PM2.5 mass concentration profile is calculated.