The Evaluation Of National Economy In Port Investment Benefit

China is one of the important countries of pacific region, there are many port cities, many developing opportunities and still many problems. In order to develop port cities effectively, we must measure the port's contribution to city's economic growth scientifically, especially for China. Therefore the evaluation of port's contribution to city's economic growth has double significance, which is theoretical and practical. In theory, it fills up the gap of this field, and builds up an easy evaluation method through the innovation. In practice, each port city can find the validity between port and city to make out where it locates and how to solve the problems. Otherwise the government can realize each national port city and establish related management policies.This thesis begins from the port functions about transport, storage, logistics, trade, industry and commerce. There are 3 steps in world port development.Secondly, the thesis studies the general relationship between port and city. Because port has many functions, such as transport, logistics, trade, industry, commerce, etc., it contributes to city economy in many ways. In this paper, a new concept "port city life circle" is put forward, explaining the different developing steps and models which a port city will go through. Next, this paper analyses the port-city relationship. At the end of this chapter, this paper explains national port cities play an important role in region economy.And then, 14 coastal port cities are selected as representatives to analyze. This paper appraises and analyzes both the ports' and cities' economy validity by DEA method, using matrix, putting them into 4 categories, explaining different conditions of ports' contribution.In following, it introduces the concept of port investment benefit, which divides into macro-investment benefit and micro-investment benefit. It applies national economic calculation theory, multiplier method and transport economics in the analysis of port investment benefit. It introduces their core ideas, explores the method how to calculate port and related industries contribution to city's economy. Inaddition, we take an example for Shandong port group and calculate how much the port investment affects GDP rate. From this example, we can easily find out how important our ports work on cities' economy.Finally, we get a conclusion that we must enhance infrastructure of port. The contribution of port industry and related industry is very significant to national economy development, and the social benefit of port industry and related industry is so large even out of people's imagination.