A combined Raman/elastic backscatter lidar observations is carried out in the Pearl River Delta (PRD) China. The results show the largest lidar ratios of the order of 80 sr in the uplifting boundary layer in 2-3 km during the haze period. In the moderate pollution period, the lidar ratio has an average value of 58 sr. The Angstrom exponent exhibits high values around 1.82, indicating the presence of rather small particles. Different back air mass trajectories and the ambient atmospheric conditions are attributed to the distinct characteristics of aerosol optical properties in the haze and moderate pollution episodes. In the lower layer in the haze period, air masses are mostly advected from southeast coast China. In contrast, the air mass in the moderate pollution observing period passes through northwest China, indicating the combination of some pollution from the Tarim Basin in case of strong convection and the smoke from adjacent fire burning spot in PRD region.