Abstract: The Aerosol Extinction Coefficient, Atmospheric Boundary Layer, Aerosol Optical Depth in summer of Chengdu were retrieved by making use of the observed data from Meter scattering micro-pulse Laser Radar in Chengdu, June-August2017, and the law of daily and monthly changes of aerosol extinction coefficient, distribution characteristics and influencing factors of Aerosol extinction coefficient were studied combining with the sun photometer observations, Surface particulate concentration and atmospheric visibility data. The results showed that the daily variation of the aerosol extinction coefficient wassignificantly affected by human activities and the daily variation of Atmospheric Boundary Layer, which exhibited the peak emerging before dawn and sunset, the second in the morning and the smallest in the afternoon. The high value of extinction was found in the near strata below 200 m and 300 m—700 m, and the observed high value of extinction at night may be related to the daily variation of particulate concentration and the relatively higher probability of local night precipitation. The Extinction coefficient inversed by Lidar consistent with the AOD inversed by photometer on each month in summer, with the extinction extreme values of each month appeared in near-surface layer of 100 m—150 m. The near-surface extinction coefficient had a better correlation with the concentration of ground particles, and the particles size the smaller and the correlation was better. The Aerosol optical thickness mainly came from the contribution of the lower atmosphere, and the Aerosol optical thickness of 0. 1—0. 2 microns mainly influenced the atmospheric extinction, however, extinction effect of aerosol in the atmosphere not only related to the particle concentration, but also related to the physical and chemical properties of particles.