Submerged plants are an important component of aquatic ecosystems and play a significant role in the matter cycling and energy flowing of aquatic ecosystems. The coverage and biomass of submerged plants are key parameters for evaluating the stability of shallow water systems such as lakes. Owing to the echo detector has the feature of high efficiency and no damage monitoring, it has been used in submerged plant coverage monitoring. Its accuracy algorithm has also received more and more attention. Hangzhou West Lake, a shallow lake that submerged plants restored successfully, was chosen in this study. The BioSonics portable echo detector-MX was used to collect submerged plant echo samples. It combined with the artificial sample setting simultaneously, the submerged plant samples corresponding to the echo detection spot location are collected to verify the accuracy of the echo detection results. By establishing regression model, the relationship between the percentage of submerged plant volume (PVI) and the corresponding average fresh weight respectively obtained by echo detection and artificial sample was analyzed, the results show that the two parameters have good correlation. Interpolation analysis was carried out on the coverage data of submerged plants through the same season of different lakes and different seasons of the same lake in the unacquired area by using three interpolation methods called Ordinary Kriging, Inverse distance weighted interpolation and Radial Basis Function (RBF). The interpolation results are cross-validated to ensure the accuracy of the method. The accuracy of three methods are Inverse distance weighted interpolation > Radial Basis Function > Ordinary Kriging. The results will provide the technical support for monitoring submerged plant using the echo detection and interpolation analysis methods combined in large-scale shallow water bodies.