Abstract: As Vehicular ad hoc networks has a special node type and channel characteristics,using the traditional Ad hoc network routing protocol can not achieve satisfactory performance．In order to realize high speed and reliable data transmission rate,it is needed to study the emerging routing algorithms．Geographical location aided routing based on greedy algorithm is the mainstream of VANET routing．This paper mainly studied the routing protocol based on the geo-graphic location, improved GPSR(Greedy Perimeter Stateless Routing) routing protocol.Introduced the concept of vectors to improve the routing protocol GPSR greedy forwarding mode,i.e. the choice of the next hop node considers not only the distance from the destination node but also the urban environment crossroads node.Moreover,added predictive models to predict the movement of vehicles at intersections and improve the efficiency of routing protocols.

Key words: VANET(Vehicular ad hoc networks),Road topological,GPSR(Greedy perimeter stateless routing)