To combat global warming, “carbon neutrality” has gradually become a consensus. Some countries have constructed domestic and regional carbon trading markets, and links to global carbon markets are receiving increasing attention. Blue carbon, an important component of nature-based solutions (NbS), has not received the attention it deserves and is still isolated from the carbon trading market. Based on summarizing the existing achievements of blockchain application in carbon trading, this paper analyzes how to make each participating body provide services in the process of blue carbon production, circulation and trading, and designs the architectural diagram of the blue carbon system under peer-to-peer (P2P) transactions based on the theoretical framework of blockchain 3.0. Utilizing the advantages of decentralization, high transparency and non-tamperability of blockchain, we can realize a highly efficient, low-cost and intelligent blue carbon trading management system. Thus, we can make the world pay more attention to the development and utilization of marine resources and increase investment in blue carbon sink projects; and promote the development of blue carbon market, enrich the carbon trading market, and help achieve “emission reduction without reduction in production”.