Abstract: To have a comprehensive understanding of the group psychological changing process after major accidents and to provide a theoretical basis for public safety incident prevention and control, a systematic research on group psychology of major accidents was conducted. Firstly, from the theoretical level, the formation process of group psychology in major accidents was discussed based on the connotation and attribute of major accidents, group and group psychology, and the psychological impact of major accidents on group was analyzed. Then, the types of group psychology in major accidents were concluded, and a tree model was built for group psychological events in major accidents based on development stages of major accidents. Finally, according to the attributes of public safety incident, a system of factors influencing group psychology in major accidents was put forward. The results show that the stages of a major accident are different from each other in their influences on the group psychology, and that the influencing factors of the major accident on group psychology mainly include enterprise factors, triggering factors, incident crowds and forming stages.

Key words: major accidents, group psychology, public safety, event tree, psychological changes