Abstract: To solve the shortest path problem on large-scale complicated networks is very difficult because it will use a mass of time and storage space. It is related to application systems about geographic information systems. After analyzed a lot of shortest path problem Common algorithms and based the classic Dijkstra algorithm, a kind of algorithm to calculate the shortest path in discretional two spot was realized. The experiment has indicated that the optimized algorithm has shortened 80% on calculation time and decreased one order of magnitude on used space by comparing with the classic Dijkstra algorithm.