Synthetic Aperture Radar Interferometry (InSAR) technique shows huge potential in the deformation monitoring of coastal seawalls, which is essential to guarantee the safety of people's lives and social property. However, a single view InSAR dataset can only identify satellite-oriented point-like targets (PTs), and the one-dimensional deformation would cause deformation estimation deviation and potential risk undetected. This study developed a multi-view InSAR analysis method to present the first 3D deformation monitoring and structural-level deformation analysis of coastal seawalls. The density and accuracy of selected PTs are improved by a spatial-temporal similarity-based multi-view PTs joint extraction method, and the deformation accuracy is improved through a parallax entropy weighted 3D deformation inversion method. Taking the Donghai Seawall as an example, the 3D deformation of the seawall is revealed, indicating a rapid-slow-steady deformation process.