Abstract: Knowledge flow is one of the most important and the most basic form in innovation activities, innovation is the result of knowledge flow and knowledge flow has been becoming the current hot issues. As an important carrier of knowledge flow among the innovation actors, innovation network has become the core area of economic geography. This paper based on the perspective of economic geography, reviewing the related research achievements of scholars at home and abroad, which contains the rise of the knowledge flow and the relationship between innovation network of different spatial scales and knowledge flow. The results show that the researches of knowledge flow are more and more fruitful, but the dynamic mechanism and the space effects of knowledge flow on innovation performance, and the problems of the impact of different knowledge types on the formation and evolution mechanism of innovation network of different space scale remain to be further researched.