Abstract: Under the background of increasingly strict environmental policy constraints, green investment has become one of the means for port and shipping enterprises to improve their competitive advantages. The investment of enterprises has an impact not only on their own profit, but also on the profit of other members in the supply chain around the port. The shipping supply chain is taken as the research object and the different scenes of investment are introduced. It analyzes the effect of cost, investment, economy and market of investment efficiency on the port supply chain. Finally, it analyzes the influence of different investment strategies on consumer surplus and social welfare. Therefore, in this paper, a port supply chain model is constructed, in which the port is Stackelberg leader and the carrier is the follower. The four cases are studied respectively: no investment; port investment; carrier investment; the both investment with port and carrier. With discussing and comparing the results, the conclusions are as follows: (1) Port investment of green technology will increasing the cost from supply chain member; (2) When the efficiency of technology investment is gradually improved, the level of green investment is declining, and reducing the cost of green inputs, thus achieving the investment effect of "investing in high efficiency, low input level, and high overall growth"; (3) Whether the carrier or the port investing in green technology will increase the service price of the market. Compared with the non-green technology investment, the green technology will increase the demand of the overall market; (4) From the perspective of consumer surplus, the carrier’s green technology investment will be less than the consumer surplus generated by the port green technology investment, and it will also reduce the adverse effects caused by the price “transfer effect” to a certain extent; (5) From the perspective of social welfare, green investment may lower overall social incomes. The social welfare of carrier investment is better than that of port green investment. However, from the perspective of environmental protection, the government’s policy making has a higher priority, which is conducive to improving environmental benefits. The research results have enriched the research of the green investment of port and shipping enterprises. It can provide a reference for the investment choice of the port supply chain members who reasonably balance the investment efficiency. This also has guiding significance for the development of the green port supply chain.

Key words: shipping supply chain; green investment; investment efficiency; investment decision