By analyzing monitoring data of atmospheric pollutions in Meiyu season measured by AML-2 mobile lidar, we study the temporal and spatial distribution characteristics of aerosol and ozone in troposphere over Hefei in Meiyu season, and analyze the effect of precipitation on pollution reduction. The results show that the aerosol extinction coefficient is small in Meiyu season and decreases with the increase of altitude on the whole. At 0.5 km, the extinction coefficient is from 0.1 km-1 to 0.18 km-1 in multiple days in Meiyu season. Continuous precipitation plays a significant role in reducing aerosol concentration, the mean aerosol extinction coefficient before Meiyu season and in Meiyu season is 0.37 km-1 and 0.14 km-1, respectively. The temporal and spatial variation characteristics of ozone are obvious in Meiyu season. The ozone concentration decreases with the increase of altitude and shows large daily variation. In June 20 and 24, 2008, the difference of mass concentration of ozone at 0.4 km is about 59.5 μg/m3. Compared with concentration of ozone before Meiyu season, the concentration in Meiyu season is greatly reduced with the maximum difference up to 41.8 μg/m3 at the same height.