With the wide application of global navigation and location technology, people have growing demands of solving the shortest path problem. In the real traffic network, all kinds of traffic information have greatly influenced path searching, such as traffic jams. So existing algorithms just remove the congested road and recompute the path. So the traveler needs to wait for a period of time. In order to solve the optimal path in road network with restricted routes quickly, this paper proposes an incremental algorithm and an optimized algorithm based on A* algorithm. Area Hierarchy Tree and A* search strategy are adopted in these incremental algorithms. The experiments with real datasets show that the incremental algorithm is reliable and highly effective for optimal path planning of real constrained road networks.