With different criteria,inland always selects a harbour which is considered as most suituble to export its goods.The resulting economic hinterland becomes the social and economic base to realize export trade and affected harbours development.The criteria may be least-distance,least-time,least-cost,or their combination,etc,Also because of the increase or decrease of harbour's handling capacity,the extension or interruption of traffic lines at sea or at land.,the technical innovation,the variation of traffic cost,etc.,the economic hinter land is varied and changed dynamicly.