Abstract: The technique of synthetic aperture radar interferometry (InSAR), with development more than a decade, has been widely used in various fields of earth sciences. GAMMA, one of the most popular application software, adopts two-rail differential approach to process the SAR data in the experimental area with registration, filtering, flat-earth removal phase, unwrapping and differential treatment, and finally get vertical deformation map, achieving surface deformation monitoring. The SAR data of this study is from ESS-2 satellite, with DEM resolution of 30 meters. The minimum cost flow method is adopted to unwrap the deformation in the direction of radar sight line, and then generate the vertical deformation map. The result shows that subsidence is notable in the city and its surroundings in the study area but rare in the mountainous area.