Abstract: Medical emergent events have complex causes. Media anomie behavior can greatly influence the development of public opinion and sometimes lead to public crisis. To explore the media anomie influence on online public opinion evolution process, this paper bases on agenda setting, and chooses the grounded theory to analyze the online text materials from online public opinion on a typical medical emergency crisis. Research model is built according to the study. The result shows that the evaluation process of medical emergency crises’ public opinion includes 7 sections, thus, media motivation, event report, public reaction, expert reaction, public opinion reverse, event quell and secondary risk. Therefore, purifying media motivation, managing information resource reliability, popularizing medical knowledge and managing secondary risk topics will be very meaningful in the process of online public opinion control management.

Key words: Medical emergent events, 　Agenda setting, 　Media anomie, 　Online public opinion, 　Evolution process