Since the institutionalization of science, the production mode of scientific knowledge has experienced the evolution from "academic science" to "post-academic science". The role of scientists has changed from the traditional single "academic scientists" to "post-academic scientists" with multiple role modalities, including academic scientists, industrial scientists and government scientists. With the deep interweaving between scientific activities and social factors, the role orientation of different types of scientists faces many problems and dilemmas, such as role dislocation and alienation, "cross-border" issues in scientific field and social field, imperfect guarantee of role orientation system, and the public's misunderstanding scientists' role. The nature, root and countermeasures of these problems and dilemmas will be interpreted from multiple dimensions, such as promoting the unity between both scientific responsibility and social responsibility of scientific community, perfecting the coordination and cooperation mechanisms of scientists role, building a scientific ethics ruling system with practical pertinence, promoting scientific education and public participation in scientific and technological governance. It is of great significance to promote the role function of post-academic scientists and to optimize the science and technology governance.