Abstract: The polarization Mie-scattering lidar (PML) can be used for detecting the depolarization ratio of cirri and aerosol backscattering wave, and investigating the extinction characteristic of aerosols in the atmosphere. In order to improve the detection capability in daytime, a narrow band interference filter and diaphragm are employed in the system to separate the received laser return signals consisting of Mie-scattering signal and Rayleigh scattering signal from the background noise. The overall structure, specifications and measurement method of PML are described. The fundamental principle of PML is briefly introduced. The main performance parameters of PML were determined, and the results were analyzed. The typical detected results of extinction characteristic of aerosols and the structure of cirri at Hefei(117.16°E, 31.90°N) are presented and discussed. The primary observational results over Hefei show that the performance of this lidar is reliable. And it has the ability to detect the physical and optical characteristics of the cirrus and aerosols.