Abstract: The serious subsidence in reclamation area may cause inaccurate topographic survey based on bench points.Time series DInSAR is an effect method to detect subsidence velocity.We analyze the interferogram phase model,and use amplitude dispersion values and temporal coherence to select coherent points.According to the different space-time characteristics,we separate and extract the deformation phase,and detect subsidence velocity.24 Envisat ASAR images acquired from Oct.2007 to Feb.2010 were used to detect subsidence velocity.The results show that the age of Hydraulic-Fill Soil will affect the subsidence.