Abstract: The key inventor is the creator of the core technology in the organization. It is important to study the factors that influence a firm to be a key inventor from the perspective of knowledge. Based on patent data of 80 Chinese electrical & electronic enterprises during 2009 to 2015, logistic regression analysis reveals how the related variety, unrelated variety and knowledge integration capability affect the firm to be a key inventor. The results show that the related variety of knowledge base is positive with being a key inventor; while the unrelated variety of knowledge base has an inverse U –shape effect on being key inventor. In addition, the research also finds that knowledge integration capability mediates the relationship between being key inventor and both of related variety and unrelated variety of knowledge base.