A practical route planning algorithm for vehicle navigation system is proposed in this paper. the shortest path algorithm with the restricted searching area. The algorithm takes advantage of the adjacent list data structure and the mechanism of restricted searching area, that is, the algorithm uses the spatial distribution feature of the real road network to restrict the searching area in reason. Finally, combining with its practical application in Real-Time Vehicle Navigation System (RTVNS), one example is given, the analysis in theory and the experimental results show that compared with the Dijkstra algorithm, the new algorithm can greatly approve the searching speed, and satisfy the needs of RTVNS.