Abstract: Following the enactment of the Arbitration Law of the People's Republic of China (2025), ad hoc arbitration has obtained explicit statutory recognition in China. Nevertheless, its operation remains constrained by fragmented normative sources, unclear governance boundaries, and unresolved coordination between arbitration associations and arbitration institutions. From the perspective of social governance, this article examines the normative supply and functional positioning of these two actors in China's ad hoc arbitration regime through doctrinal analysis of existing legislation, local rules, and institutional guidelines. It argues that the current framework still suffers from ambiguity regarding the legal nature of the filing mechanism and from the continuing tendency of arbitration institutions to over-intervene in ad hoc proceedings. The article proposes that arbitration associations should be repositioned as self-regulatory bodies responsible for formal filing, model rule-making, and arbitrator oversight, while arbitration institutions should adhere to the principles of limited intervention and procedural assistance, acting primarily as appointing authorities and providers of ancillary procedural services. On this basis, it advocates a governance structure characterized by functional differentiation and normative coordination so as to safeguard party autonomy, preserve procedural legitimacy, and strengthen China's competitiveness in international commercial arbitration.