This research focuses on the problem of how to promote radical innovation of enterprises during the process of collaborative innovation. Taking 241 manufacturing enterprises in China as the research object, this paper empirically explores the impact of different types of R&D partners on enterprises' radical innovation and the moderation role of formal/informal appropriability mechanism. The study finds that:1) the higher the collaboration intensity with universities and research institutions is, the stronger the positive impact on enterprises' radical innovations is; 2) Collaboration with users and suppliers also has significant positive impact on radical innovation; 3) The informal appropriability mechanism of enterprises positively moderates the relationship between external R&D collaborative partners and radical innovation of enterprises. It shows that the extent to which an enterprise benefits from collaborative innovation depends on the type and strength of the innovation appropriability mechanism it adopts.