Background and Objects: Patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) are often old and poor in physical fitness. The purpose of this study was to investigate the anesthetic effect of different doses of alfentanil combined with ciprofol in elderly patients undergoing endoscopic retrograde cholangiopancreatography (ERCP). Methods: In this clinical trial, 137 patients, who were candidates for ERCP were randomly divided into three groups. Group A were given 0.15 µg/kg/min of alfentanil in maintenance stage, Group B were given 0.25 µg/kg/min and Group C were given 0.35 µg/kg/min. Mean arterial pressure (MAP), heart rate (HR), oxygen saturation (SpO2) of the patients at each time point including the entry into the operation room (T0), at the beginning of surgery(T1), 10 minutes after surgery(T2), 20 minutes after surgery(T3), 30 minutes after surgery(T4),endoscopy withdrawal (T5) were recorded. Adverse events(including respiratory depression, body movement and hypoxemia),the dosage of ciprofen, the time of operation time and awakening were recorded. Results: Compared with Group A, MAP and HR in Group B and Group C was decreased during T1-T5 (P < 0.05). Compared with group B, MAP and HR in group C was decreased during T1-T5 (P < 0.05). Compared with Group A and Group C ,the number of adverse reactions of Group B was decreased(P < 0.05). There was no statistical difference in surgical time among the three groups(P>0.05) ,but t a statistically significant difference in recovery time (P < 0.05). Conclusion: The adverse events of alfentanil 0.25µg/kg/min combined with ciprofol were low, and the anesthetic effect was the best.