This study introduces the “2+X” analytical framework to overcome the structural gap between macro-level strategies and micro-level implementation in China–Central Asia regional cooperation. By positioning Xinjiang and Tashkent as dual cores and incorporating third-party actors with comparative advantages, the framework advances cooperation from bilateral arrangements toward open, network-based multilateral governance. Based on the “Structure Mechanism Outcome” model and empirical evidence from agricultural technology cooperation, the findings demonstrate that “X” actors reduce information asymmetry, enhance institutional resilience, and promote the upgrading of regional integrated value chains. The research deepens understanding of subnational cooperation under the Belt and Road Initiative and provides a practical pathway for policy design and regional development.