Objective:To investigate the effect of intravenous esketamine combined with erector spinae plane block(ESPB)on the postoperative recovery quality in patients undergoing thoracoscopic lobectomy with general anesthesia.Methods:A total of 97 pa-tients who underwent thoracoscopic lobectomy were divided into two groups:group K(n=49)and group C(n=48),according to whether or not they were given esketamine.Patients in K group were given slow intravenous injection of 0.2 mg/kg ketamine after anes-thesia induction and 5 minutes before surgical skin incision,and patients in group C received intravenous injection of physiological sa-line equivalent to group K drugs.Comparison of general indicators,quality of recovery at 24 h postoperatively[40-item Quality of Re-covery Rating Scale(QoR-40)score],cellular immune function before and after 24 h of treatment(NK cells,CD4+T cells,and CD8+T cells),hemodynamics at each time point,and the occurrence of postoperative adverse events between the two groups.Results:Intrao-perative remifentanil dosage was lower in group K than in group C(P＜0.05).The overall QoR-40 score,as well as the subscores for pain,emotional state,and physical comfort in group K were higher than those in group C at 24 hours postoperatively(P＜0.05).Addi-tionally,levels of NK cells,CD4+T cells,and CD8+T cells were higher in the group K than those in group C at 24 hours postoperative-ly(P＜0.05).There were no statistically significant differences in hemodynamics and total incidence of adverse effects between the two groups(P>0.05).Conclusion:The intravenous application of esketamine combined with ESPB for thoracoscopic lobectomy under general anesthesia reduces intraoperative remifentanil dosage,improves the quality of postoperative recovery and improves postoperative cellular immune function in patients without increasing adverse effects.