In 2023, China’s Marine Environmental Protection Law was secondly revised, in which the extraterritorial provisions in marine environmental protection were evolved and highlighted. Through enforcing the extraterritorial provisions, it is possible for China to pay attention and control marine pollution or ecological damage that occurs beyond the territory and safeguard the national marine environment. However, China has not carried out any enforcement practices based on the extraterritorial provisions of the Marine Environmental Protection Law. As a responsible participant in marine environment governance and driven by the need to address marine environmental threats posed by foreign countries, China has a sufficient rationale for introducing extraterritorial enforcement in marine environment protection from a broader perspective. However, given that extraterritorial enforcement in the marine environmental protection field is not adopted universally, China’s future extraterritorial enforcement activities will face risks of excessive use, and a series of dilemmas may inevitably arise during the enforcement practices. Analyzing the potential dilemmas of China’s extraterritorial enforcement in marine environment protection, corresponding suggestions are provided to avert excessive extraterritorial enforcement and promote the effectiveness of extraterritorial enforcement activities to protect essential national marine environmental interests.