The outbreak of COVID-19 was accompanied by an outbreak of “information outbreaks”. In this study，3070 subjects were randomly selected in the form of a questionnaire to investigate their epidemic information transmission mode on social media，mental health status during the epidemic and the interaction mechanism between them. The results showed that social media epidemic information makes the public immersed in communication，the public experienced mass depression and generalized anxiety during the epidemic，social media “immersion” has an inverted u-shaped shpae with psychological status. The communication behavior of social media and psychological state form a mutually accelerating “top”. The more immersed the epidemic information was in social media，the more frequent the secondary transmission was，and the worse the public’s mental health was，and vice versa.