There is currently considerable interest in system leadership and how it can support school change at scale. System leadership aims to move learning beyond school boundaries through leveraging experience and expertise. The success of system leadership depends on how key educational players can move effectively between and across traditional educational boundaries. China's education system has long-established system infrastructure to support boundary spanning. This paper presents three selected different types of system leaders who span across boundaries to build relationships, interconnections and interdependencies to enhance collective teacher capacity across their systems. The paper argues that working in a centralised, top-down system creates enabling conditions which facilitate boundary practices. It further suggests that such conditions form tensions which risk reproducing static systems when leadership is enacted hierarchically. Enabling conditions include established routines, roles and values which empower boundary spanners to leverage their expertise. System tensions can arise between the centre and periphery, between responsibility and professional power and between diversity and homogeneity.