Objective To investigate the safety and efficacy of Remimazolam combined with nalbuphine in painless endoscopic mucosal resection(EMR)of colorectal polyps.Methods A total of 100 patients who undergo painless colorectal polyp EMR were randomly divided into nalbuphine combined with remimazolam(NR)and nalbuphine combined with propofol(NP),with 50 patients in each group.The mean arterial pressure,heart rate and oxygen saturation were recorded after entry(T0),1min after administration(T1),1min at the beginning of surgery(T2),3min(T3),5min(T4),and at the end of surgery(T5).The frequency of application of vasoactive drugs,their operation time,consciousness vanishing time,recovery time,the times of supplementary sedation,dosage of incidence of nalbuphine,adverse reactions,The satisfaction of doctors and patients were compared.Results The mean arterial pressure of T1,T2,T3,T4 and T5 in the NR group was higher than that in the NP group(P<0.05),and the heart rate of T1 in the NR group was higher than that in the NP group(P<0.05).The incidence of respiratory depression,hypotension,injection pain,the recovery time and the frequency of application of vasoactive drugs in the NR group was lower than that in the NP group(P<0.05).The satisfaction of doctors in the NR group was higher than that in the NP group(P<0.05).There was no significant difference between the two groups in the operation time,oxygen saturation,the times of supplementary sedation,the dosage of incidence of nalbuphineincidence of dizziness,nausea and vomiting,and other adverse reactions(P>0.05).Conclusion Nalbuphine combined with remimazolam can be used safely in the EMR,has few perioperative adverse effects,and is a good choice for painless EMR.