The research progress of seawater sound velocity models is summarized, the models are divided into mathematical models and numerical models. The mathematical models are represented by the empirical formula, Munk model and Generalized Digital Environmental Model (GDEM). The numerical models take Empirical Orthogonal Function (EOF) model as the main type and are widely used based on the global data set. The mathematical models are of good expansibility, but too ideal; while the numerical models can achieve high sound velocity fitting accuracy, but they also have limitations. Taken the sound velocity models in the South China Sea as the starting point, the research and application needs of the sound velocity models in the South China Sea are summarized, and it is believed that the sound velocity models in the South China Sea will continue to widen application and achieve new results in the direction of high-precision three-dimensional sound velocity models and dynamic prediction sound velocity models.