Objective: To explore the relationship between mobile phone addiction, fear of missing out andsocial media anxiety. Methods: Mobile phone addiction scale, fear of Missing out scale and social mediauser social anxiety scale were used to test the students from various provinces on the Internet. Results:(1) Correlation analysis showed that fear of missing out, mobile phone addiction and social media anxietywere significantly positively correlated. (2) The mediating effect test showed that the fear of missingout not only predicted social media anxiety directly, but also predicted social media anxiety indirectlythrough the mediating effect of mobile phone addiction. Conclusion: Mobile phone addiction plays apartial mediating role in the relationship between fear of missing out and social anxiety of social mediausers.