Abstract:〔Abstract〕 ObjectiveTo investigate the effect of midazolam combined with different doses of Nalbuphine hydrochloride on painless gastroscopy examination in patients with severe obesity. Methods 120 patients with severe obesity undergoing painless gastroscopy examinatin in Nanchang Fifth Hospital from January 2018 to July 2020 were selected, and were divided into control group and observation group according to the random digital table, with 63 cases in each group. The observation group was applied 2.5 mg nalbuphine hydrochloride composite midazolam; the control group was used 5 mg nalbuphine hydrochloride composite midazolam. Compared the analgesic and sedative situation of the two groups, awakening time, physical movement and complications. Results There was no significant difference between the two groups in VAS score 5 min after awakening and Ramsay sedation score 2 min after anesthesia induction (P > 0.05). VAS scores of patients in both groups decreased 30 min after awakening compared with 5 min after awakening, and the difference was statistically significant (P < 0.05); However, there was no significant difference in VAS score between the two groups 30 min after awakening (P > 0.05). Ramsay sedation score of patients in both groups was higher than that 2 min after anesthesia induction, with statistically significant difference (P < 0.05); However, there was no statistically significant difference in Ramsay sedation score between the two groups during endoscopic laryngeal entry (P > 0.05). The complete awakening time of the observation group was (5.03 ± 1.04) min, which was shorter than that of the control group (5.50 ± 1.20) min, and the difference was statistically significant (P < 0.05). There was no serious body movement in the two groups, and there was no significant difference in the incidence of general body movement (P > 0.05). The incidence of complications in the observation group was 7.94 %, lower than 20.63 % in the control group, and the difference was statistically significant (P < 0.05). Conclusion Severe obesity patients underoing painless gastroscopy examination applping 2.5 mg or 5 mg of namphhine hydrochloride composite midazolam can effectively calm the sedation, the body movement is small, but the low nalbuphine dose of hydrochloride can reduce the occurrence of complications, it is conducive to the patient to wake up.