As the first space-borne polarization lidar to observe the state of the global atmosphere, CALIOP has provided large number of first-hand data on global climate and environmental changes since being launched in 2006. It has been proved to be a promising tool in the field of atmosphere remote sensing. In this paper, the functional structure, data products, and data processing of CALIOP were introduced. Moreover, the principles and processes of layer detection, scene classification and extinction retrieval were also especially emphasized.