Typical shortest path is Dijkstra algorithm, its time complexity is O (n2). A map of the city's road network has many nodes, if we use the Dijkstra algorithm, the time complexity of the algorithm is too high and the speed of resolution this problem is slow. In order to change this situation, we are discussed from the aspects of algorithm design, puts forward the improved bidirectional search algorithm. Practice has proved that, the improved algorithm can improve the search speed and it suitable for intelligent transportation system