This study surveyed 2 350 college students from three medical colleges in Anhui Province byadopting the online social support scale，health-promoting lifestyle scale and electronic media health literacy scaleof college students to explore the relationship between online social support，e-health literacy and health-promotinglifestyles of medical undergraduates. The results showed that the network social support，electronic health literacyand health promotion lifestyle of medical undergraduates scored(70.63±17.95)，(74.96±11.89)and(117.38±21.03)respectively. E-social support was positively and significantly correlated with e-health literacy and health-promoting lifestyle(P ＜ 0.001)，while e-health literacy partially mediated between e-social support and health-promoting lifestyle of medical undergraduates，with amediating effect of 33.19%. E-health literacy can be aneffective entry point to improve the health promotion methods of medical undergraduates. This paper suggests thatmedical colleges should concentrate on teaching effective retrieval methods from authoritative health knowledgepublishing websites and official book and paper retrieval websites according to the characteristics of students’majors. In addition，medical colleges can use the peer effect and role model to improve the e-health level andpositive health promotion lifestyle of medical undergraduates.