To explore the influencing factors of eHealth literacy among medical undergraduates， a questionnaire was conducted on 2 260 medical undergraduates from three medical colleges in Anhui Province. The results showed that the eHealth literacy score of medical undergraduates in Anhui Province was（73.26± 10.82）；Multiple linear hierarchical regression analysis showed that variables including exposure to health promotion - related courses，educational level of the mother，grade level，being as the only child，and gender. There were also motivational factors including health self - management ability，self - rated health status and attitude towards health，and online self - efficacy in efficacy factors were all influencing factors of eHealth literacy of medical undergraduates. Mediation effect analysis revealed that online efficacy partially mediates the relationship between health self -management ability and eHealth literacy. From the perspective of the eHealth use interaction model，it is crucial to give a full play on the role of motivation factors and efficacy factors to promote the effective management of self-health of medical students to improve their self-rated health status and health attitude，boost their online self-efficacy，and therefore improve their eHealth literacy level.