To overcome the changes in port environment, the M&A of shipping companies and terminal operators, enlargement of ocean ships, the ports take a new strategy, the co-opetition, that is a neologism coined to describe cooperative competition. In order to work out the specific co-opetition strategy for the four ports in Liaoning Province: Dalian, Yingkou, Jinzhou and Dandong, the paper first analyzed the current situation of the four ports, and then it spread out the superiority and inferiority of the four ports by using SWOT analysis methodology, finally it suggested that the four ports should carry out their co-opetition strategy in some aspects, such as strengthening cooperation over feeder services among four ports and clearing assignment of responsibility according to commodity.