Abstract: As an emerging governance mechanism, digital platform plays an important role in China's social governance. However, existing studies have underestimated the social impact of this important empirical phenomenon, without providing a theoretical explanation of how the digital platform enables the integration of social governance. Through investigating the experience and exploration of platform-based social governance in many regions, using interviews with key participants and research on policy documents, the article abstracts "multi-level mediation across organizational boundaries" to summarize the internal mechanism of digital platform's effective empowerment of social governance. On the one hand, digital platform manages the relationship between the party and the league, digital platform enterprises, the public and other entities and government departments in external coordination, expand the scope of solving public problems by mobilizing resources. On the other hand, the digital platform manages the diverse members of the government through internal coordination, links the data, channels and resources of different members of the government as an obligatory passage point (OPP), and cultivates the awareness and trust of cooperation around specific social issues. The outlook of this article lies in how to construct effective interaction mechanisms, enhance conceptual consistency and cultivate knowledge and abilities that match actors, which will be potential directions to break through the bottleneck of digital platform empowerment.