Abstract: Chlorophyll a concentration (Chl a) is an important component of phytoplankton, and its vertical distribution is of great significance to the estimation of marine primary productivity and the study of underwater radiation transfer process. Based on in situ data collected from several cruises in the Bohai Sea and the Yellow Sea, we analyzed the characteristics of vertical distribution of Chl a. The results indicated that the vertical distribution of Chl a in the Bohai Sea and Yellow Sea is mainly composed of uniform distribution type and gauss distribution type. The uniform type dominated in spring and winter, while gauss type dominated in summer. Consequently, a classification strategy which is based on sea surface temperature and surface Chl a was proposed for identify the vertical distribution type of Chl a. The model could effectively distinguish uniform type from gauss type with an overall accuracy of 82%. Furthermore, for gauss distribution type, a gaussian model was proposed. The model showed good performances with more than 85% samples of the R² was > 0.8, and more than 90% samples of the mean absolute percentage error was < 30%. Meanwhile, we established models for estimating the parameters of gaussian model from marine environmental parameters (surface Chl a and water depth).