Tianshan is selected as the study areas. Based on the aynthetic aperture radar interferometry technology, two Digital Elevation Models (DEM) were generated by processing the data obtained from radar satellite TanDEM-X and ERS respectively. Then the SRTM DEM was combined with 1∶5 million digital elevation model standard of our country, the accuracy of the two DEMs was compared and analyzed. Because of the complexity of the study area, the dramatic changes of the height and the dense vegetations, the overall difference between the two generated DEMs and SRTM DEM is large, the standard deviation is 11.55 m and 16.74 m respectively. However, it’s obvious that the accuracy of DEM generated from TanDEM-X data is higher. The conclusion is that the data obtained by TanDEM-X has obvious advantages over the ERS in terms of extraction DEM in complex topography areas.