Abstract:The Cryosat-2 altimetry waveform measurements on the sea ice are retracked using the 40% threshold method in the Arctic Ocean. By combing the waveform parameters and the sea ice concentrations, the sea ice and the Lead (open water between the ice floes) are identified effectively. The sea ice freeboard is determined by along-track searching and an interpolation algorithm| it is compared with the AWI results, and the variations of the mean freeboard of the first-year and the multi-year sea ice area between 2011 and 2013 in the Arctic Ocean are given. The comparison results show good correlation in the corresponding period of each year.