Abstract: D-InSAR (Differential Synthetic Aperture Radar interferometry) technology is available day and night. It can provide high-resolution images and realize continuous spatial coverage. Based on two-track differential interferometric, this paper analyses 7 scenes TerraSAR-X to get the D-InSAR data of surface subsidence of a mine in Shandong province, and then compares with the leveling data. On account of the differential value between the D-InSAR data and leveling data and the distances, this paper obtains the modified formula of D-InSAR data using the least-square polynomial fitting method. And after the modification, the accuracy of the D-InSAR data meets the requirements of surface deformation monitoring, which holds broad application foreground.