Land subsidence has a significant impact on urban safety, making it crucial to investigate this phenomenon. However, due to limitations in data coverage and research methodologies, the spatiotemporal distribution of land subsidence across Shenzhen remains unclear. Multi-temporal interferometric synthetic aperture radar (MT-InSAR) technology was used to process a total of 534 Sentinel-1A SAR images from three different frames (P11F71, PI13F71, PI1F65), resulting in the generation of subsidence rate maps and subsidence time series that comprehensively cover the entire city of Shenzhen. Significant subsidence regions were then extracted, and the temporal evolution of subsidence in these areas was analyzed. By integrating optical imagery reflecting human activities on the earth's surface, the subsidence mechanisms in the identified areas were deduced. The results show that land subsidence in Shenzhen is primarily caused by construction activities, with the most significant subsidence occurring in the western coastal areas, reaching a maximum rate of 80 mm each gear near the estuary of Dongbao River. The cumulative subsidence from March 2017 to June 2023 amounted to 500 mm. The expansion of the Qinglinjing Reservoir has led to increased water demand, significantly raising formation pressure and causing land subsidence. InSAR-based land subsidence monitoring and analysis in urban areas can address the spatial and temporal resolution limitations of traditional monitoring methods, providing effective recommendations for large-scale subsidence prevention and control.