Abstract: This article discusses the design and implementation of a vehicle navigation system (VNS), which is based on the joint technology of GPS and GIS.After a general systematic analysis of VNS, this article discusses the following issues:(1)The outline design of VNS including its hardware, software and system architecture.(2) The real-time procedure of GPS signals and other ones, which involves signal receiving, data communication, coordinate transformation, as well as the processing of electric compass signals.(3) The data organization issues.Both spatial and attribute data of roads network are organized into an integer model.Point features are also organized in the same way.In order to make effective spatial index and topological relationship, some relevant technologies has been developed.Optimized data organization and multithread programming technology has made possible the fast rotation and movement of the map in response of GPS signals.Based on road topology, we develope a fast algorithm to search best route.(4)The matching of GPS signal with map data.Normally, GPS coordinate error is around 100 m, which includes system error.We use GIS data to correct the systematic error and to fit the GPS coordinate into the map.In case GPS signal is lost, we employ some algorithms to estimate the position of the vehicle, with the aid of other devices like electric compass.(5) The design and implementation of our VNS interface.The VNS interface is mainly composed of three views:global view that presents the map in a normal mode and highlights the planned and passed route, a driver's view that rotates to keep the forward direction northward;and a prompt window that shows user guidance information.(6)The audio control part, which can fulfill the need for man-machine interaction better than traditional ways of keyboard plus mouse.