Abstract: There are some deep tensions in the reform process of modernizing social governance in China's megacities,which are highlighted by the lack of convergence between institutional innovation and mechanism support,the dilemma of synergy in the policy network,and the difficulty of control allocation in the digital transformation.These triple tensions are intertwined and mutually reinforcing,which have a complex impact on the governance innovation of megacities.This paper provides an in-depth analysis of the organizational mechanism of the multiple tensions,on the basis of which it expands and enriches the connotation and policy focus of the systemic reform view.Finally,this paper points out that future reforms need to view governance innovation from a continuous historicist perspective,and promote synergistic changes between institutions and mechanisms; take incentive compatibility and process reengineering as the breakthrough point,and build a more integrative social policy network; and take a more fine-grained upper and lower division of government as the principle to promote a multi-party governance pattern under the overall layout.