To explore the effect of social support in nurses who have depression during public health emergencies in tertiary medical institutions.This retrospective analysis was conducted in Wuhan from July 2021 to December 2021. We distributed a self-made demographic questionnaire, Depression Scale (CES-D 10), Social Support Rating Scale (SSRS), and Psychological Capital Questionnaire (PCQ-24) through Questionnaire Star, and conducted a questionnaire survey with nurses in multiple tertiary medical institutions during the public health emergency in Wuhan. At the same time, a questionnaire survey was conducted with the general population during the public health emergency in Wuhan through the Self-made demographic questionnaire and Social Support Rating Scale (SSRS) issued by questionnaire star. In the end, 1052 valid questionnaires were obtained, including 526 valid questionnaires for nurses and 526 valid questionnaires for the general population. The social support scores of nurses and the general population were analyzed. The association between social support and nurse depression was analyzed by multiple linear regression. The asymptotic policy was used to examine social support as a potential mediator of the association between psychological capital and depressive symptoms.There were no remarkable differences in age, marital condition, monthly revenue, professional title, occupational condition, smoking, and drinking among nurses (all P>0.05). The impersonal social support score, support utilization score, and total support score of nurses were lower than in the general Chinese population (P<0.05). Both lower subjective support scores and lower objective support scores of nurses were interrelated with major depressive symptoms (β=0.257, P<0.01; β=-0.314, P=0.026). Regression analysis with psychological capital as the independent variable and social support as the control variable showed that social support was negatively correlated with depressive symptoms (β=-0.205, P<0.01), social support had a positive moderating effect on the relationship between psychological capital and depressive symptoms (β=0.047, P<0.05). Self-efficacy was taken as an independent variable in regression analysis, after social support was added as the control variable, social support was negatively interrelated with depressive symptoms (β=-0.118, P<0.01), and self-efficacy was negatively interrelated with depressive symptoms (β=-0.251, P<0.01), the effect between social support and self-efficacy was interrelated with depressive symptoms (β=0.144, P<0.05). Hope was taken as an independent variable in regression analysis, after social support was added as the control variable, social support was negatively interrelated with depressive symptoms (β=-0.296, P<0.01), and hope was negatively correlated with depressive symptoms (β=-0.157, P<0.01). When the social support dimension was added, the effect of psychological capital on depressive symptoms increased (P<0.01).Social support is a key external intervention factor to alleviate nurses' depressive symptoms, and psychological capital is a key internal positive psychological support resource to combat nurses' depressive symptoms. Social support can increase the influence of psychological capital on depressive symptoms.AJTR Copyright © 2022.