An automated method for sea route design based on electronic chart is developed to improve the security and reliability of planned sea route. First, the obstacle projection matrix is built based on the environmental information provided by electronic chart. Then a basic path is built quickly by using the adjacent relation among girds. Finally, elastic algorithm was used to optimize the basic path. And the safe shortest route is generated. Results from experiments demonstrate that the proposed method has advantages such as stability and efficiency and can be applied to route plan in large sea area and complicated sea condition.