Abstract: A polarization Mie lidar has been developed for measuring profiles of depolarization ratio of cirrus clouds and dust aerosols. The fundamental principle of the polarization lidar was briefly introduced. Overall structure and specifications of the polarization lidar were described as well as measurement and data processing methods. The typical observational results of depolarization ratio and structure of the cirrus over western suburb of Hefei were presented and discussed. The optical properties of the cirrus were also described. The primary observational results showed that the depolarization ratio for cirrus clouds varies from 0.2 to 0.5 within the altitude range of 6～10 km, and the lidar has the ability to measure the optical properties of cirrus clouds and their temporal and spatial v