In order to extract the ocean dynamic parameters from shallow water, water depth, and current inversion at multiple (three or more) sites, HFSWR (high frequency surface wave radar) sea echo is developed. In this paper the inversion principle and theoretical model are presented in detail, and the proposed idea is verified for three or more than three sites, which shows prospects in practice. By analyzing the data collected from three HFSWR detection experiments in northern Jiangsu province, the inversion results show good performance, which is promising for extracting ocean water depth in inner zone and shallow water by HFSWR in engineering application.