Abstract: The occurrence of exhibition security accidents is the result of the mutual coupling factors of "man-machine-environment-management". This study is going to elaborate 11 influencing factors of exhibition security accidents from four aspects, i.e., man, mechanical equipment, environment and management. With the help of grey relational analysis, this study evaluates the importance degree of the affecting factors in exhibitions. The result shows that affecting factors of facilities and equipments failure is of the greatest importance degree and site maintenance personnel, site design, building material quality are the secondary important factors; another important factors are safety management body, social environment, activity organization management, safety management system, natural environment and event participant behavior which are considered as the third important ones. Evaluation of the importance degree of affecting factors on exhibition security incidents will provide a theoretical basis for exhibition security control.