The piers and navigable holes of bridges arranged in navigable waters limit the navigation of ships，and thus the demarcation of bridge area scope is of great significance to guide the safe navigation of ships.We analyze the influencing factors for the bridge area scope delimitation by sorting out the navigation restrictions in the current bridge area laws and regulations.According to the influence of the bridge piers on the navigating ships in the waterway，we design the methods for calculating the width and length of the bridge area scope based on the ship domain theory，which can demarcate the bridge water area scope according to the bridge and waterway characteristics，and realize the one bridge one policy.The method is used to demarcate the bridge area scope in the Yangtze River.The results show that compared with the traditional method of bridge area scope demarcation，the method proposed in this paper can not only ensure the safety of ships sailing in the bridge area but also reduce the navigation constraints of the ships near the bridge while avoiding the waste of shoreline resources.