Abstract: Synergy innovation is manifested as the knowledge flow cross organization in the innovation network. Relationship is the channel of knowledge flow, and relational governance is an important means to promote knowledge flow. With the method of cross cases, such as TD alliance, Shanlian alliance and Changfeng alliance, this paper analyzes the process of relational governance driving knowledge flow based on the view of knowledge process and knowledge situation. And then explores its driving mechanism. It has been found that: Firstly, relational governance structure promotes knowledge flow through relationship capitalization. Secondly, relational governance structure promotes knowledge flow through relationship humanization. Thirdly, relational governance means promotes knowledge flow through relationship socialization.