Abstract: Urban land subsidence is a kind of slowly developing geological disaster and has sustained negative impacts on the social economy and human life. Therefore, it is of great significance to carry out effective and wide-area urban subsidence monitoring. With 34 high-resolution TerraSAR-X SAR images obtained from April 07, 2009 to December 14, 2010 as data sources, the land subsidence in Tianjin City was monitored using the differential interferometry of time series based on interferometric point target analysis (IPTA) in this study. Then the monitoring precision was verified using the precise leveling data, and a verification method of subsidence time series based on least-squares fitting was adopted. Finally, subsidence analysis and interpretation were carried out based on the verification results. Compared to the leveling data, the root mean square errors of the subsidence rates obtained using IPTA and that using the least squares-fitting of time series were 3.15 mm/a and -3.25 mm/a, respectively. According to the analysis of subsidence results, the overall subsidence of the study area is significantly uneven, the maximum subsidence rate is -128.41 mm/a, and the spatial-temporal distribution of the land subsidence correlates highly with surface cover types and groundwater exploitation.