Abstract: Satellite laser altimetry can quickly and efficiently obtain the 3D coordinate data of ground points with high precision elevation, but the laser was inevitably affected by clouds in atmospheric transmission. Firstly, echo waveforms were fitted according to the echo energy data recorded in the atmospheric transmission process by the geoscience laser altimeter system(GLAS). Secondly, the differential zero-crossing method and Fernald method were used to realize cloud detection and cloud optical depth inversion respectively. Finally, moderate-resolution imaging spectroradiometer(MODIS) data and aerosol robotic network(AERONET) ground station data from Beijing region were employed to perform a validation analysis. The results show that the method presented in this paper has a high credibility in the optical depth inversion of the cloud by laser altimetry satellite. In the actual situation, the cloud optical depth inversion error is less than 0.1, and when the cloud optical depth is less than 1, the relative error is far less than 0.01. The relevant conclusions are of reference value for the quality control of the laser altimetry data of domestic satellites.