Objective To explore the moderating effects of social support and digital health literacy on the relationship between social media use and cardiac anxiety among young elderly patients undergoing percutaneous coronary intervention （PCI）, and to provide evidence for developing individualized interventions. Methods A total of 387 young elderly (aged 60 to 74) patients undergoing PCI were recruited by convenience sampling.Data were collected using the Social Media Use Behavior Scale, the Social Support Rating Scale, the Digital Health Literacy Instrument, and the Cardiac Anxiety Questionnaire.Pearson′s correlation analysis, sensitivity analysis, and hierarchical regression analysis (with simple slope test) were performed. Results The total score for cardiac anxiety was 27.03±9.09.Sensitivity analysis identified educational level and number of stents implanted as confounding variables. Hierarchical regression and simple slope test revealed that social media use behavior positively impacted cardiac anxiety, and social support and digital health literacy jointly moderated the relationship between social media use behavior and cardiac anxiety （P＜0.05）. Conclusion Cardiac anxiety among young elderly patients undergoing PCI is relatively low.Nursing staff should tailor interventions aimed at enhancing social support or digital health literacy based on differences in patients′ social media use behavior to alleviate cardiac anxiety level.