Objective To observe the effectiveness and safety of alfentanil combined with different doses of remazolam for painless hysteroscopic treatment. Methods Sixty patients undegoing painless hysteroscopic treatment from January 2021 to February 2021 were randomly allocated into the two groups with 30 cases in each group. Alfentanil 10μg/kg+ remazolam 0.15mg/kg was used in Group R1 and alfantanil 10μg/kg + remazolam 0.2mg/kg was used in Group R2. Hysteroscopic treatment began after the patient's eyelash reflex disappeared. If a single dose of remazolam did not meet the sedation requirements, 2.5 mg of remazolam was added at the appropriate time. Patients' blood pressure (BP), heart rate (HR), pulse oxygen saturation (SpO2) and respiratory frequency (RR) before anesthesia, 3min after induction and the time point of cervical dilation were recorded. The time spending for induction and awakening, intraoperative body movements, adverse reactions, incidence of uterine contraction pain and the patient's satisfaction in the two groups were also compared. Results Patients in Group R2 had shorter induction time, smaller changes in BP and HR (P＜0.05), and less intraoperative movements than patients in Group R1 (P＜0.05). There was no statistical difference in awakening time and departure time, adverse reactions incidence of uterine contraction pain and patient satisfaction between the two groups. Conclusion Afentanyl 10μg/kg combined with remazolam 0.2mg/kg can be effectively used in painless hysteroscopic treatment.