Objective To compare the clinical effectiveness of mini-midline catheter versus peripheral intravenous catheter in older patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) for stone removal.Methods A total of 140 older patients undergoing ERCP for stone removal were chronologically divided into two groups, with 70 in each group.The control group received intravenous infusion using peripheral intravenous catheter, while the observation group used mini-midline catheter inserted under ultrasound guidance for infusion.The catheter insertion time, indwelling duration, incidence of complications, and patient satisfaction were compared between the two groups.Results The observation group required more catheter insertion time than the control group (P＜0.05).However, the observation group had longer indwelling duration, lower incidence of phlebitis, leakage at the puncture site, and catheter blockage, as well as higher patient satisfaction compared with the control group (all P＜0.05).Conclusion Although mini-midline catheter requires a longer insertion time compared with peripheral intravenous catheter, it is associated with a lower incidence of complications and a longer indwelling duration.Thus, mini-midline catheter better meets the intravenous infusion needs of older patients after ERCP for stone removal.