Abstract: In order to optimize the intelligent ship routing problem, improve the speed of operation on maps with large amounts of data, and consider the navigation characteristics of ships, an improved A^* algorithm based on a quadtree grid model is proposed. Firstly, the quadtree adaptive resolution image processing algorithm is employed to analyze and integrate navigation information in the chart. And the navigable area, restricted navigation area and unnavigable area are marked and divided more efficiently. Secondly, in consideration of the characteristics of ship navigation and environment,the distance penalty function is added to A^* algorithm. The penalty value is calculated by use of the distance between candidate nodes and obstacle nodes. And the cost model of grid object is established in the quadtree adaptive resolution raster object. Finally, The proposed algorithm is illustrated for the path planning of a container ship with single propeller on two charts. The proposed A^* path planning algorithm performs well in terms of computing speed and ensuring safety between obstacles.