Digital elevation model can provide abundant topographic information, which is an important basic data for studying ecological environment, geology and geomorphology, surface deformation monitoring and so on.In this paper,SRTM DEM is used as reference DEM, and the digital elevation model of Poyang lake is retrieved by using the dualpolarization radar image of four -view Sentinel -1, and the topographic results of this region are updated and reconstructed.From the aspects of visualization and accuracy, the DEM inversion results of VV polarization and VH polarization are compared and analyzed based on mountain shadow map, contour map, coherence coefficient map and mathematical fitting model.The results show that it is effective to extract the topography of Poyang lake by radar image,and the elevation information of the lake bottom area can be extracted well.The resolution of the digital elevation model is 13.90 m, which is 53.67% higher than that of the reference DEM.Based on the linear mathematical model and the quadratic mathematical model, the fitting analysis of the inversion results of VV polarization mode and VH polarization mode is carried out.The coefficients of determination are 0.93 and 0.94 respectively, indicating that the DEM results of inverse performance of the two polarization modes are highly similar, and could both exactly reverse the topographic results of the study area.The reversed results of lake bottom’s topography can provide data support for water conservancy departments to carry out river and lake management.