Schematic and system parameters of AML-2 mobile lidar for monitoring atmospheric pollutants are presented. Fundamental principles of lidar and its data processing methods are detailedly analyzed. The vertical profiles of SO2 , NO2 , O3 and aerosol over Hefei are presented. The vertical density of SO2 and NO2 are somewhat lower, but the vertical density of ozone has obvious time evolution and is relevant to the solar radiation. The height of boundary layer top has obvious diurnal variation. The characteristics of pollutants profiles are discussed with some meteorological parameters.