Abstract: In recent years, port environmental pollution has become increasingly serious. As a core enterprise in the port supply chain, port enterprises play an important role in promoting the construction of green harbors. Based on mandatory emission reductions, economic performance and environmental performance have been taken into account to build an evolutionary game model of a local government with port companies’ emission reductions. The model introduces carbon tax as a penalty factor and considers the government’s regulatory costs and corporate rent-seeking costs. By analyzing different equilibrium states, the effects of government regulation and punishment on both parties’ strategies were discussed. The results show that the optimal Nash equilibrium strategy is the government does not fully supervise and port companies reduce emissions. The government can decide whether to adopt full supervision by adjusting the relationship between the intensity of supervision and the unit carbon tax, which will affect the decision of port enterprises to reduce emissions. To a certain extent, it provides an effective reference for promoting the construction of green ports in the future.

Key words: compulsory emission reduction, green port, evolution game, regulatory cost, enterprise rent-seeking