The invention discloses a method for expressing the processing of roads on a map. The method comprises the following steps: 1, importing road data of a map; 2, classifying roads; 3, coding the map vector data of the roads and giving the polygonal expression, particularly, creating three surface polygon models of road polygons, crossing polygons and road isolation zone polygons, two point models ofcrossing nodes and road blind end nodes and a line model of road center line, and coding the features of each road polygon model, creating an attribute table for the three major road models of points, lines and surfaces, and generating the map vector date in a compressed format at the same time; and 4, decoding and displaying the database. The invention has the advantages of simple method, low data redundancy, strong data analysis function and high graphic transmission speed, and meanwhile, the invention further has the advantages of high road classification accuracy and low cost. The invention can fully present the complicated urban road system through the different classification of surface road elements and the creation of road models.