Abstract: A new approach is presented to distinguish the polygon's vertex being concave or convex and calculate the polygon's simple ratio.Then a novel method for extracting polygon's features is proposed in this paper.First,we extract polygon's topology features-the number of vertex and the concave-convex quality,on the basis of them,we can recognize polygon qualitatively,and the method is insensitive to noises.Then we extract polygon's geometry features-parallelism,parallel edges' ration and simple ratio,as a result,we can analyze polygon quantitatively,and the algorithm can show fine discrimination between polygons.The effectiveness of the algorithm is demonstrated preliminarily by computer simulation.