As urbanization progresses, the influence of frequent human activities such as construction and groundwater exploitation on the stability of urban surface is gradually deepening. Based on Sentinel-1A data from March 2018 to December 2021, the land subsidence rate and time series of Guanghan were obtained by using the small baseline subset interferometry technology, which combined with the method of extracting high coherence points by the amplitude dispersion index in permanent scatterers interferometry technology, and the analysis of settlement characteristics and causes in Guanghan was conducted. The results show that during the research period, almost 90% of Guanghan do not suffer from severe subsidence, Xiaohan Town, Jinyan Street, Sanxingdui Town and Xiangyang Town experience small-scale settlement. In addition, the settlement in and around the construction area is relatively serious, with a maximum settlement rate of -31 mm/a. Furthermore, settlement mainly occurs between 2018 and 2020, and construction activities and precipitation are the main factors causing land subsidence.