Objective To observe the effect of different doses of esketamine on early mood in pa-tients with preoperative anxiety after thoracoscopic surgery.Methods Eighty patients with preoperative anx-iety before thoracoscopic surgery,37 males and 43 females,aged 25-64 years,BMI 18-26 kg/m2,ASA physical statusⅠ-Ⅲwere selected.According to random number table,the patients were randomly divided into four groups:control group(group C),esketamine 0.1 mg/kg group(group E1),esketamine 0.2 mg/kg group(group E2),and esketamine 0.3 mg/kg group(group E3),20 patients in each group.In groups E1,E2,and E3,the patients were slowly injected with corresponding doses of esketamine intrave-nously 30 minutes before the end of the operation,and the patients in group C were given 10 ml of normal saline at the same time.The 7-item generalized anxiety disorder scale(GAD-7)score and hospital anxiety and depression scale(HADS)score were evaluated 24 hours before surgery,24,48,72,and 120 hours af-ter surgery,respectively.Peripheral venous blood(5 ml)was collected at the same time points,and serum brain-derived neurotrophic factor(BDNF)concentration was detected by ELISA.NRS scores at rest and ex-ercise were recorded 12 and 24 hours after surgery.The number of remedial analgesia and the number of ef-fective compressions of analgesia pump within 48 hours after surgery were recorded.Results Compared with group C,the scores of GAD-7 and HADS in groups E1,E2,and E3 were significantly decreased 24,48,and 72 hours after surgery(P＜0.05).And compared with groups E1 and E2,the scores of GAD-7 and HADS in group E3 were significantly lower(P＜0.05).The serum BDNF level in groups E1,E2,and E3 were significantly increased compared with group C 24,48,and 72 hours after surgery(P＜0.05).Compared with group E1 and E2,the serum BDNF level in group E3 was significantly higher(P＜0.05).Compared with group C,the NRS scores at rest 12 and 24 hours and the scores at exercise 12 hours after surgery in groups E1,E2,and E3 were significantly decreased(P＜0.05).And compared with groups E1 and E2,the scores in group E3 were significantly lower(P＜0.05).The number of postoperative remedial analgesia and the number of effective compressions of analgesia pump in groups E1,E2,and E3 were signif-icantly decreased compared with group C within 48 hours after surgery(P＜0.05).And compared with groups E1 and E2,the number in group E3 was significantly lower(P＜0.05).Conclusion Single intra-venous injection of esketamine 0.1,0.2,and 0.3 mg/kg can improve early postoperative mood of patients with anxiety before thoracoscopic surgery,and esketamine 0.3 mg/kg has better anti-anxiety effect.