Abstract: The geometrical and optical properties of cirrus cloud with multiple scattering were studied and the retrieval methods of cirrus height and lidar ratio were improved. An approach was proposed for determining cirrus height based on multiple scattering factors and the extinction coefficients of cirrus were corrected by the factors. With multiple scattering factors and the extinction coefficients, the error of the cirrus-height was computed. Finally, the precise lidar cloud detection retrieval was achieved preliminarily. In the improved method of retrieving the lidar ratio with multiple scattering, the nonlinear equations with cirrus lidar ratio and cirrus extinction coefficient as variables were constructed, and the particle swarm optimization algorithm was used to solve the equations, the extinction coefficient of the cirrus's top and the lidar ratio of cirrus clouds were acquired. Then, through the PLATT's multiple scattering equation and the ratio of total scattering and signal scattering calculated by semi-analytic Monte Carlo method, the lidar ratio was obtained. The experiment was carried on based on the proposed method, using the real return signals of the ground-based lidar. It is turned out that the proposed technique has the advantages of high accuracy. Therefore, it has a promise future.