Cirrus clouds have an important effect on the radiation balance between the earth′s surface and the atmosphere. The properties such as cloud structure and optical depth of cirrus clouds are investigated and the detectivity of different wavelengths to cirrus clouds is analysed by using observations obtained from the three-wavelength lidar system in Hefei for the period from January 2011 to October 2012. The results show that the lidar with longer wavelength among 355, 532, 1064 nm has the better detectivity for cirrus. The peak height of cirrus clouds over Hefei is lower in winter and higher in summer with a mean value of about 8 km; and the average cloud thickness ranges from 1 km to 2 km. The cirrus optical thicknesses detected by the three different wavelengths are nearly the same, conforming that the extinction coefficient of cirrus cloud is independent of the wavelength. Most of the cirrus clouds over Hefei are thin cirrus clouds whose optical thicknesses are less than 0.3, and the mean values are about 0.12.