The traditional subject theory of international law takes the nation-state as the center, and constructs a binary or ternary structure system with the sovereign state as the basic unit, intergovernmental international organizations as the derivative subject, and individuals as the limited object. This subject theory under the Westphalian system, with the deep evolution of globalization, is faced with structural dilemmas such as the lack of “global commons” governance, the rise of non-state actors, and the lack of a protection mechanism for human common interests. As an important ideological resource for China to participate in global governance, the concept of “community of human destiny” is not only a political vision, but also contains a profound reconstruction of the subject theory of international law. This paper holds that the concept of “community of human destiny” breaks through the logical limitation of traditional reciprocal justice between countries by establishing “human” as an integral value attribution, introducing the dimension of “relational subject” into the structure of international law, and realizing the paradigm leap from “coexistence law” to “cooperative symbiosis law.” This concept is not a simple denial of the national subject, but a higher-order legal interest form of “community,” which imposes normative constraints on “obligations to the world” and “common concerns of mankind” on the basis of recognizing national sovereignty, thus completing the transcendence and development of traditional international law at the subjective level.