Objective:To analysis the impact of public health emergencies on mood fluctuations of depression and the related factors in the elderly in Shanghai, in order to provide a new evidence for early psychological intervention.Methods:A cross-sectional survey was conducted among 983 elderly in the Department of Geriatrics of Xinhua Hospital Affiliated to Shanghai Jiaotong University and two communities in Changning and Hongkou Districts of Shanghai by using a self-compiled social life questionnaire and Geriatric Depression Scale(GDS-30)during corona virus disease(COVID)-19 outbreak from 1 February to 15 February 2020.The mood fluctuations of depression and the related influencing factors were analyzed by comparing the current GDS-30 scores with the scores within previous six months.Results:Of 983 questionnaires, 867 were valid.The incidence of mild fluctuations of depression was increased from 20.9%(181/867)to 27.2%(235/867)during the public health emergencies( P<0.05), with 3 cases of newly emerged severe depression.The GDS-30 scores were higher during the public health emergencies than before the emergencies(9.88±3.85 vs.7.67±3.54, P<0.05). The four risk factors inducing fluctuations of depression in the elderly were the number of coexisted chronic diseases ≥2( P=0.036), the lack of visits or communication from families( P=0.015), the family members exposing a risk to COVID-19( P<0.01), and the daily viewing of epidemic news more than 4 h( P=0.023). Linear regression analysis showed that cough, sore throat, dizziness, sleep disturbance and dyspnea were significantly related to the aggravation of depression(based on the increase of GDS-30 score)( P<0.05). Conclusions:Public health emergencies may exacerbate depression in the elderly.They are more likely to experience the aggravation of depression when they suffer from multiple chronic diseases, lack the child visits or communications, have the family members exposing a risk to COVID-19 and pay excessive attention to the epidemic.