From the perspective of patent, this paper constructs a theoretical model between knowledge diffusion rate and enterprise knowledge search breadth, and probes into the relationship between them. At the same time, this paper explores the adjustment functions of these variables including the technical difficulties and the market expectation .Through the analysis of the patent data,we came to the follow conclusions: the diffusion rate of knowledge has a positive effect on the breadth of enterprise knowledge search. The difficulty of technology and the degree of decentralization of innovation sources positively modulate this promotion effect. The market expects this role to be negatively regulated.