Abstract: In order to realize the monitoring of deformation in the urban area of Hohhot city, this paper uses the permanent scatterer synthetic aperture radar interferometry （PS-InSAR） technique to perform temporal interferometric processing on 25 scenes of Sentinel-1A data from March 2017 to April 2021 in the urban area of Hohhot city to extract the surface subsidence information in the urban area and analyze the causes of subsidence in the main subsidence centers. The results show that there are five obvious centres of subsidence in the urban area of Hohhot, and that the overall average annual surface subsidence rate is 3.65 mm/a, with an average cumulative subsidence of 15.50 mm. The subsidence is mainly due to over-exploitation of groundwater. Given that the free Sentinel-1A data has the advantages of short time baseline and sufficient number of images, it is conducive to InSAR time series analysis, which can meet similar urban surface deformation monitoring work and serve urban safety.