Objective To investigate the depression status and quality of life (QoL) of patients with severe obesity who have undergone bariatric surgery and to evaluate their potential correlation.Methods A total of 50 patients with severe obesity who had undergone elective bariatric surgery in the general surgical ward of Peking Union Medical College from January 2013 to December 2017 were enrolled in this study. The general data were collected. The patient's depression status and QoL were assessed by the Zung's Depression Self-Assessment Scale and the SF-36 Quality of Life Scale,respectively.Results The depression score was (44.85±9.07) scores in these 50 patients,including 38 patients (76%) without depression and 12 (24%) with mild depression. The scores of the mental-emotional,physical,psychomotor,and psychological barrier dimensions of patients with severe obesity were (3.70±1.25),(18.65±4.10),(4.25±1.35),and (18.75±5.46)scores,respectively. The physiological function score of patients with mild depression was (95.83±10.21)scores,which was significantly higher than those without depression (68.42±38.95) scores(F=6.209,P=0.011). The vitality and mental health scores were (46.67±14.72) and (57.33±14.68) scores in patients with mild depression,which were significantly lower than those [(65.79±21.94) (F=4.867,P=0.030) and (75.16±17.21) scores (F=0.212,P=0.032)] in patients without depression. Correlation analysis showed that the mental-emotional score was positively correlated with physical score in patients with severe obesity (r=0.503,P=0.015),whereas the depression score was negatively correlated with the general health status (r=-0.430,P=0.032),vitality (r=-0.594,P=0.002),social functioning (r=-0.455,P=0.022),mental health (r=-0.562,P=0.003),and QoL score (r=-0.439,P=0.028).Conclusions The QoL is remarkably affected by depression in patients with severe obesity before surgery. Assessment of the mental status of patients with severe obesity may help to identify this problem and thus improve the QoL.