Abstract: As urban development shifts from incremental expansion to stock renewal, mixed land use has become a core instrument for easing spatial resource constraints and advancing refined governance. Its governance focus has consequently shifted from whether mixed use should be adopted to the systemic question of how mixed use can be made effective, adaptive, and smoothly convertible. This paper traces the conceptual evolution of mixed land use from physical superimposition and functional integration to systematic governance, then analyzes the practical dilemmas of stock renewal around the central issue of flexible conversion and dynamic adjustment. It develops a tripartite space-rights-governance framework: the spatial dimension follows the logic of land-category allocation, cadastral management, and land-value assessment; the rights dimension follows the logic of property-rights clarification, interest balancing, and value-increment sharing; and the governance dimension follows the logic of multi-stakeholder co-governance, cross-departmental coordination, and sustained oversight. Four implementation pathways are proposed: use regulation and flexible control, rights coordination and property-rights innovation, benefit balancing and value sharing, and organizational optimization with long-term supervision. The study offers a theoretical framework and practical reference for refined mixed-land-use governance in the stock-renewal era.