Abstract: This paper analyzed the knowledge diffusion model proposed by Xu Yu and considered the model follows an increase rule that is the same with the condition of accruement. However, in parallelism with the accruement, when the factor of effort of knowledge diffusion by the managers in corporation is considered, the model cannot explain the knowledge diffusion rule. The mechanism in the course of knowledge diffusion was analyzed and the knowledge diffusion model was modified. The modified model concerns the factor of the manager's effort and concludes that the knowledge-non-owned would be requested to receive correlative train, so knowledge diffusion would keep to the first-fast-then-slow rule in the course of diffusion.