Abstract: The idea of people-centered development has increasingly become the dominant logic of grass-roots governance. Based on the continuous deepening of reform in the work of handling complaints in Beijing, taking the "Downward transfer and Mass Evaluation" work in Pinggu District, Beijing as an example, this paper explores the mechanism of party building leading multiple entities to participate in social governance, and focuses on how to guide the masses to become the main body of grassroots governance. It has found that the practical mechanism of "three-governance integration" in the new era is shaped by governance subjects embedded in the organization, the socialization of acquaintances in governance units, the respect for public and private restraints of governance rules, and the interactive integration of governance mechanisms, which provides an important guarantee for the systemic governance and the source governance. From the passive governance to the initiative governance, and then to the autonomous governance, the people really become the initiators of governance issues, the participants in its process, the winners of its effectiveness, and the supervisors of the governance. This is a vivid practice of people's democracy in the whole process, which reflects that the grass-roots level is moving from passive citizen appeal-driven to people's subjective governance.