As the important infrastructure for a country's foreign trade and economy, and the hub of the communication complex, ports play a pivotal role in the development of national economy and transportation system. The coordination between the port industry and national economy should and must be fully emphasized. Along with the growth of ports and economy of China, the incoordination between the ports and the regional economy has gradually emerged. In order to solve the problem that the development of China's transportation system is lagging behind its economic development, the issue of coordinated development of ports and national economy must be fully stressed. This paper begins with an analysis on the status of ports in the national economy and argues the necessity of the coordination between ports and national economy. An analytical model is then established to explain this necessity by using grey correlation theory. Suggestions and measures for the coordinated development are given in the end.