Abstract: The basis on which a seaport depends for existence and development is its hinterland.Hinterlands may be divided into two types:the direct hinterland only belonging to a specific port,and the complex or overlapls hinterland,i.e. several hinterlands can simultaneously use a certain port.Thus the property and development of any port,as well as its character and scale are not only closely related to its own specific regional background,but also affected by other relative ports,especially the adiacent ones.In other words,all ports have their econo-mic geographic bases respectively. The categoies of the regional background of ports consist of:(1)the hi-nterland and its link with the port in traffic and transport.(2)the condition of mineral resources in the hinterland.(8)the level of development and the type of economic structure in the region directly affected by the port.(4) the scal of the city which the port relies on.(5)the natural condition of the harbour and neig hbourring region.(6)the location of the port,etc.All the factors above mentioned act to the ports in different way and varying degree Because the relative ports,especially the neighbourrings,have an overla-pping complex hinterland,the shipping goods can be tran sf ered to anyone of them.This brings naturall’y an influence each other on their development.In fact, they check each other and have respective roles to play.Finally the regional combination of the port co nstitutes’1a regional port group~I. This paper analyses and assesses the regional background of the ports,and makes an approach to the regional port combination,so as to get a clear under-standing about their action on the seaports~ fo rmation,development and distri-bution.All of these provide scientific basis from point of view of geography for rationally planning and locating seaports.