Abstract: Phase unwrapping is an important step in interferometric synthetic aperture radar(INSAR).By using local Radon transform,this paper put forwards a kind of method for phase unwrapping of INSAR which based on the same phase path searching.A method for phase correcting by setting reference phase of the ground is also given.The method given in this paper has the advantages of stability and less error,which is very useful and realistic in phase unwrapping.By using the L band data of SIR-C of the Three-Gorgess area of China,the local DEM(digital elevation map) is obtained.