This study aimed to determine the values of the half‐effective dose (ED50) and 95% effective dose (ED95) of remimazolam besylate used in the procedural sedation of endoscopic retrograde cholangiopancreatography (ERCP). Sixty patients who fulfilled the inclusion and exclusion criteria of this study were selected. Sufentanil was administered intravenously and remimazolam besylate was administered 2 min later. ERCP treatment was feasible when the modified alertness/sedation (MOAA/S) score was ≤2. If choking or movement occurred during duodenoscope placement, it was considered as a positive reaction. The dose was increased in the next patient; otherwise, it was considered as a negative reaction, and the dose was reduced in the next patient. The ED50 and ED95 values and 95% confidence interval (CI) of remimazolam besylate were calculated by Probit regression analysis. All 60 patients completed the trial. The ED50 and ED95 values of remimazolam besylate were 0.196 and 0.239 mg/kg, respectively, for the procedural sedation of ERCP. The time of MOAA/S score ≤ 2 was (82.58 ± 21.70) s, and the mean time of awakening was (9.03 ± 5.64) min. Transient hypotension was observed in two patients without medical intervention. The ED50 and ED95 values of remimazolam besylate used in the procedural sedation of ERCP were 0.196 and 0.239 mg/kg, and the dose of the medications has definite efficacy and good safety.