Abstract: There is a tradition: science knowledge is created by expert. They guarantee all the knowledge first and pass them to public as gatekeepers. The rise of Wikipedia changes the history of knowledge into public producing. This paper rethinks the cognitions of scientific knowledge communication from a distinct angle of social constructivism. It indicates that democratic consciousness and scientific image secularization influenced by media revolution both played significant roles in overturning expert tradition. Wikipedia as a social media guarantees social construction and provides probability of a diverse community producing scientific knowledge. It also would help science reflection, especially in defusing knowledge controversies between science and public.