大型港口发展到一定规模后,港口企业进一步扩大规模会受到成本快速增大和环境条件的限制,边际效益必将出现递减。因此,港口企业应该在本行业内或相关行业寻找收益更高的投资领域,在保证自身优势的前提下,通过对外投资的方式,获得新的盈利空间,使港口企业的发展突破业务种类的限 Large-scale port development to a certain scale, the further expansion of the size of the port business will be subject to rapid cost increases and environmental constraints, the marginal benefit will inevitably decline. Therefore, the port enterprises should find more profitable investment fields in the industry or related industries. Under the precondition of guaranteeing their own advantages, the port enterprises should gain new profit-making space through the ways of overseas investment so as to make the development of port enterprises break through the limit of business types