Abstract: In intelligent traffic navigation or dynamic path abduction systems, the shortest path searching is the basic function. According to the nature of road net of a city, the database structure describing the city road net is studied. Based on the database structure and the need of a GIS system, the road information is collected. Then Dijkstra algorithm is used to realize fast searching of the shortest path. The electronic map of Guangzhou is presented to show an example of city raod searching, the time of a shortest path searching result, which includes 61 crossings, being about 2.2 s.