The ICESat-2/ATLAS employed a micro-pulse multi-beam photon-counting laser altimeter system for the first time. ICESat-2/ALTAS was significantly different from ICESat-1/GLAS in terms of detection mechanism, data processing methods and the breadth and depth of data applications. Firstly, the key configuration parameters, data and products of ICESat-2/ATLAS were introduced. Secondly, the key technologies of noise removal and classification algorithms for ICESat-2/ATLAS data as well as the adaptability and problems of each algorithm were elaborated. Thirdly, the applications of ICESat-2/ATLAS data in ice sheet and sea ice elevation measurement and change monitoring, ground elevation and forest height extraction, forest biomass estimation, lake level and storage change monitoring were summarized. Finally, the development trend and prospect of photon-counting LiDAR data processing methods and applications were expected.