Abstract: Small spatio-emporal baseline PS-nSAR technology controls the time baseline and the vertical baseline at the same time to avoid the loss of time and space related issues to a certain extent. This article uses the small spatiotemporal baseline PS-nSAR method to monitor land subsidence in the Beijing region, analyzes regional land subsidence in the evolution of time series and the impact of extraction of groundwater, and the fault zone to land subsidence. The results show that the ground subsidence in time series has a clear seasonal variation, reflecting the extraction of groundwater as the main reason leading to land subsidence. The ground subsidence also depends on the impact of faults. The central area of surface subsidence and depression cone of groundwater level are not completely match, which may has a close relationship with the thickness of the compressible soil.