Abstract： Based on 44 COSMO-SkyMed satellite image data, the deformation information in the built-up
area of Nanning from 2013 to 2016 is acquired by PS-InSAR technology. To verify the accuracy of PS-InSAR monitoring, we makes a field survey and detailed analysis of the deformation characteristics and reasons in view of the representative mutation areas. The results are as follows: The deformation rate in the study area is between -7－5 mm/a. The mutation points are mostly located in the area within the Nanning ring expressway, especially Qingxiu, Xixiangtang and Xingning districts. Among them, the land subsidence is obvious in the intersection area of Xinzhu road and Sixian road in Qingxiu district and the entrance and exit area of Minzu avenue, with a settlement rate of over -9 mm/a. Combining the engineering construction data and optical historical images, the results of the field investigation are in agreement with the problems reflected by the PS-InSAR monitoring data. The purpose of this paper is to provide new ideas for the government to forecast and prevent land subsidence disasters.