A new method about how to classify different aerosols by lidar measurements is proposed. Two lidar equations including the optical parameters about background aerosol and cloud are built. The inversions about the two lidar equations are given to classify the background aerosol and cloud. The lidar signals related to two different aerosols, with two different extinctions to backscatter coefficient ratios (Saer1,Saer2), are simulated. The inversions about the two simulated lidar signals are obtained. The background aerosol and cloud are measured by lidar, and the two different aerosols are obviously classified according to the analyzed measuremental results by using this method. The simulation and measuremental results verify the effectiveness of the method for aerosol classification.