Abstract: To address the problems of huge areas, lack of data, and time urgency that are usually present in the Regional Crustal Stability(RCS)assessment, this paper presents the InSAR method to gain the elements of RCS and assess RCS. This method has the advantages of large area coverage, backtrack observation and high-efficiency. A major project in the Alxa area is used as example. We selected 25 periods of ASAR/ERS synthetic aperture radar data from 1996 to 2010. We recognize the geo-hazards and ground water fluctuation by D-InSAR centimeter-scale deformation. Then we analyze the tectonic activation by IPTA-InSAR millimeter-scale deformation. Furthermore, used the geological background, the RCS is assessed. Study results prove that InSAR is an effective new tool to assess the RCS under limited condition.