This paper proposes an improvement in the efficiency of the use of a path planning algorithm in large scale road networks. This was achieved by addressing three aspects: hierarchical layers of road networks with sub areas in each layer, selection of the layer entrance point, and the use of bidirectional search technology. This led to a new heuristic bidirectional hierarchical path planning algorithm. The algorithm was tested using Beijing road data, which showed that the time and space efficiency of the new algorithm improved significantly compared to classical algorithms. It also proved that it is reasonable to combine different kinds of path planning algorithm acceleration technologies, and that their effects can be superimposed.