OBJECTIVE To investigate the effects of esketamine combined with dexmedetomidine used for drug-induced sleep endoscopy in patients with obstructive sleep apnea syndrome. METHODS Totally 60 patients with obstructive sleep apnea syndrome were randomly divided into control group and observation group ，with 30 cases in each group. Anesthesia induction scheme of control group included loading dose of dexmedetomidine 1 μg/kg，pumped for 10 min，maintained at 1 μg（/ kg·h），and intravenous administration of propofol at a constant rate of 3 mg（/ kg·h）until the patient snored. That of observation group included same administration route and dose of dexmedetomidine as control group ，intravenous administration of esketamine 1 mg/kg at a constant rate of 0.5 mg/（kg·h）until the patient snored. Sleep endoscopy was performed when the bispectral index （BIS）was lower than 75 and the alert /sedation（OAA/S）score was higher than 1. The vital signs ，BIS and OAA/S scores of patients in awake state （T0），10 min load dose of dexmedetomidine infusion （T1），at the time of examination （T2）and at the end of examination （T3） were recorded ，as well as the patient ’s medication （including the one-time success rate of examination ，the number of additional drugs due to physical movement during examination ），and the occurrence of adverse events after medication. RESULTS In the comparison between groups ，the pulse oxygen saturation （SpO2）and BIS of patients in the observation group were significantly higher than those in the control group at T1，T2 and T3；the heart rates and mean arterial pressures （MAP）at T2 and T3 were significantly lower than those in the control group ；and the OAA/S score at T1 and T2 were significantly higher than those in the control group （P＜0.05）. Comparison within the group ，the heart rates at T1，T2 and T3 in the observation group were significantly lower than those at T0，and the MAP at T2 and T3 were significantly lower than that at T1（P＜0.05）；in control group ，compared with T0，SpO2 decreased significantly at T1，T2 and T3，heart rate decreased significantly at T1，and MAP increased significantly at T2（P＜0.05）. Sixty patients successfully completed drug-induced sleep endoscopy after medication. The one-time success rate of examination in the observation group was significantly higher （No.191460443） than control group （P＜0.05），and the number of additional drugs due to physical movement during examination was significantly less than control group （P＜0.05）. There was no significant difference in the incidence of adverse events between 2 groups（P＞0.05）. CONCLUSIONS Esketamine combined with dexmedetomidine has less respiratory inhibition and less effect on hypoxia hemodynamics in patients with obstructive sleep apnea syndrome. It has less intervention times in the process of sleep endoscopy ，and has more advantages than propofol.