How the sharing economy can move toward sustainable development is an important research topic. This paper attempts to explore the mediating effect of ecosystem strategy on the relationship between sharing characteristics and sustainable development performance by applying the structural equation model and questionnaire survey of 90 sharing-economy enterprises. The research results show that the ecosystem strategy plays a complete mediating role in the relationship between sharing characteristics and environmental performance, a partial mediating role in the relationship between sharing characteristics and social performance, and an insignificant mediating role in the relationship between sharing characteristics and economic performance. The research results provide new knowledge for research on the sustainable development of the sharing economy, which are of certain reference value for the sustainable development of sharing-economy enterprises, and government’s support to and supervision of the sharing economy.