Abstract: A polarization-mie lidar (PML) with 532 nm single wavelength able to quantitatively measure extinction and polarization characteristic of aerosol was described. There were three way to validate measurement performance of PML: First, several main performance parameters of PML were determined, which indicates that performance of the system is reliable; Second, the measurement results of aerosol by PML and RML were compared, and they show good agreement; Finally, a good agreement between lidar measurements and solar radiometer measurements was gained in detecting aerosol optical depth. The validation results show that PML is steady and its measurements are reliable. The detected results of depolarizationratio for cirrus clouds over Hefei from February to May, 2005 were also presented and discussed. The cirrus clouds were generally found to be located at 7～12 km altitude and their depolarization ratio varied from 0.25 to 0.50 with average 0.35±0.07.