On the basis of related literature review for the theories of knowledge transfer and knowledge stock, the article proposes the issue of knowledge transfer efficiency in knowledge alliance. By game model, relative hypothesis are put forward. And by case study of Zhengzhou aluminum industrial alliance , the mechanism model of knowledge transfer efficiency is constructed. It thinks that the knowledge stock has inverted U shape relationship with knowledge transfer efficiency. With the increase of knowledge feedback, knowledge stock appears a growing trend. Knowledge feedback shows a positive moderating effect on the relationships between knowledge stock and knowledge transfer efficiency. The results are helpful to explore the mechanism of knowledge transfer efficiency, which is great importance to understand the internal running law in knowledge alliance ,and also to guide enterprises to grasp its behavior of knowledge transfer in-depth.