Core enterprise is the center of Green Supply Chain (GSC) and it helps partners to meet the environmental standards and to improve GSC’s performance. However there are two questions for core enterprise when it establishes GSC: What roles do core enterprise play in GSC? How does core enterprise improve GSC’s performance? What criterions are considered when core enterprise chooses partners in GSC?   In order to answer these questions, this paper will use following methods: firstly, Analytic hierarchy process (AHP) and Analytic network process (ANP) have be used to study on three research companies (IKEA, TOYOTA and Apple); Secondly, six interviews with research companies’ employees.   After case study, the results show that when core enterprise chooses partners, it will draw up some criterions and sub-standards for partners to fulfill. Furthermore, core enterprise plays the roles as GSC’s builder, director, coordinator, and designer in the system.   Finally, this paper answered the research questions: Firstly, in order to improve the performance of GSC, core enterprise should direct all partners in GSC to save materials and recycle waste in each link of GSC. Secondly, core enterprise can use four criterions to choose partners. These criterions are: environmental management performance, product-related elements, production-service levels, and enterprise culture.