Abstract: Based on behavioral immune system and planned risk information seeking model, this study explored the mediating role of fear in the relationship between perceived vulnerability to disease and rumor belief. A sample of 661 people were recruited to complete Perceived Vulnerability to Disease Questionnaire, The Fear of COVID-19 Scale, and Rumor Belief Scale. The results show that:(1) Perceived infectability, fear and rumor belief were positively correlated with each other; Germ aversion was positively correlated with fear, negatively correlated with rumor belief. (2) Perceived infectability not only positively affected rumor belief, but also indirectly affected it through the mediation effect of fear. (3) Germ aversion negatively affected rumor belief and fear made a suppressing effect between them. In conclusion, the effects of perceived infectability and germ aversion on rumor belief were different, and fear played a mediating role and a suppressing role respectively.