Abstract: Based on the vector module’s characteristics of invariance of translation and rotation coordinate transformation，a new fragment matching method is brought forward.Firstly，the images of fragments are pretreated in order to get boundaries.Secondly，after calculating the values of vector modules which are composed by every two points in boundaries and arranging them in extracting boundary order，the longest matching segments which are the matching boundaries are found.Finally，also in accordance with the nature of invariants of modules，because some coordinates of points and modules have been known，the rest coordinates of boundary points in target coordinate system are solved based on solution of equations.Experimental results show that the method with simple principle，easy programming and rapid calculation speed is effective.