With the development of national marine strategic plan,the demand of underwater high-precision positioning is increasing greatly.Acoustic wave,as an information carrier,plays an important role in underwater high-precision positioning.In this paper,the method of determining sound velocity in seawater and several classical models for calculating sound velocity are introduced.The indirect method is used to calculate the sound velocity of sea water,that is,the sound speed is calculated by the sound velocity empirical model according to the depth,temperature and salinity.Then,several classical sound speed models are used to select the optimal model under different computational conditions,and the most suitable model for the study sea area is obtained.Calculation of sound velocity profile based on the real time observation data of Argo measured by the official website combined with the optimal classical sound velocity model.The sound velocity is corrected by the weighted average sound velocity method and the layered ray tracing method,and the depth of the sea is recovered.Results show that the accuracy of tracking method is higher than that of the weighted average sound velocity method,which can achieve decimeter level precision in depth.The error between the calculated depth and the actual value by using the weighted average sound velocity method is large.