Abstract: Featured by abundant spatial types, complex social relations and diverse stakeholders, structural green space in China’s mega cities faces a series of arising problems and challenges in spatial governance. This research firstly clarifies the concept of structural green space and, through studying relevant literature at home and abroad, has the spatial governance model of structural green space in world’s mega cities divided into two dominant prototypes: the “top-down centralized” model and the “bottom-up decentralized” model. On this basis, this research, by virtue of the “actor-tool-mechanism-content” governance analysis framework, conducts a multi-dimensional analysis of the two cases including Pudong section of the outer-ring road greenbelt and Zhangjiabang green wedge in Shanghai City, revealing the benefits and limits of the two spatial governance models just mentioned. The research finds that, in view of the current decentralization arising from administration streamlining and power delegation by local governments, fragmentation caused by urban spatial variation, and diversification of stakeholder classification, it is difficult to achieve ideal governance of structural green space merely relying on government, market or society. The research further proposes that, the “networked” fine governance model may become the future development direction for spatial governance of structural green space in China’s mega cities, which can provide useful experience and implications for related theoretical and practical work.