The simulation study is conducted based on Mie scattering theory as well as the relationship between the cirrus extinction characteristics, the effective lidar ratio and wavelengths. Data of observation is measured to calculate the effective lidar ratios of different wavelengths by three-wavelength lidar system in the western suburbs of Hefei from January 2011 to October 2012. Both the theoretical and experimental results show that in regard to the three wavelengths 355,532,1064 nm, the extinction coefficient of cirrus cloud is independent of the wavelengths, and the effective lidar ratio increases as the wavelength increases. The effective lidar ratio of cirrus cloud in Hefei ranges from 10~70 sr, and the mean value of three-wavelength is (21.0±9.3) sr, (29.4±11.7) sr and (38.1±11.4) sr. The effective lidar ratio of cirrus cloud measured by 355 nm wavelength is the lowest in autumn, while that measured by 532 nm and 1064 nm are the highest in autumn.