Abstract: A method of vectorization of scanning map based on Voronoi diagrams was described. It traced pixel（grid units） of boundaries of map elements by contour tracing technology based on black and white binaryzation for image in some layer of scanning map, and extracted end of segments on boundaries by scanning endpoints. Then according to the basic points getting from pretreatment, constructed Voronoi diagram. Finally, described the decision rule of skeleton according to the numbering mechanism and the storage structure of Voronoi, finished vectorization through extracting skeletons from the set of edges of Voronoi according decision rule of skeleton. The experiments show that the method proposed could well process more complex scanning map, supply the actual demand in rate and accuracy.