The pandemic of COVID ? 19 has significant impact on the condition of mental health and social support of medical students. However，the mechanism of medical students’mental health affected by social support during the pandemic is still unclear. In the present study，Kessler10 and social support rating scale were employed to conduct the empirical research of mental health and social support of medical students from 3 medical schools. The results indicated that students from nursing discipline，senior year and low?income families were found to have higher possibilities of developing a mental problem. Medical students’mental health was statistically significantly correlated with social support under the pandemic. Therefore，a mental health screening program among medical students and a mental health network are recommended to build to find out population mental health condition and imply targeted intervention strategies according to the risk level. New social support systems should be explored to increase the level of social support among medical students.