Abstract: Under the era of knowledge economy, knowledge transfer plays a vital role for the performance of Industry-University-Research-User (IURU) collaborative innovation. This article introduces the modularity theory aims at studying the knowledge transfer issue of IURU collaborative innovation, in which the design modularity combining organizational modularity are respectively crossed for the discussion of mechanism of knowledge transfer. Moving forward, an empirical case of Haier is adopted to further analyze its practices of collaborative innovation as well as modularity innovation (product & organization), and therein the knowledge transfer coordination mechanisms are also discussed. There are some conclusions: (1) modularity can not only help promote IUR switch from “face-to-face” to “side-by-side” collaborative innovation, but adjusts the knowledge transfer strategy among partners; (2) while module interface could act as one of effective channel for harmonizing information asymmetric issue and implementing knowledge transfer. The outcome of this study could be of reference for China enterprises during their exploration of IURU mode as well as implementation of knowledge transfer.