The study investigated the effect of a low dose of sufentanil (0.1 μg/kg) on the effective sedative dose of ciprofol to achieve a BIS <60 during induction of anesthesia in 48 elderly patients. Patients were randomly divided into group S + C (sufentanil + ciprofol, 23 patients) and group C (only ciprofol, 25 patients). The initial dose of ciprofol was 0.3 mg/kg, subsequent doses were adjusted by 0.05 mg/kg according to the sequential method up and down. The estimated ED50 of ciprofol was 0.075 mg/kg (95% CI: 0.024–0.123 mg/kg) in the S + C group and 0.267 mg/kg (95% CI: 0.159–0.361 mg/kg) in the C group. The ED95 reached 0.246 mg/kg (95% CI: 0.141–14.566). mg/kg) in group S + C and 0.439 mg/kg (95% CI: 0.340–67.768 mg/kg) in group C. The addition of sufentanil reduced the need for ciprofol by 44%–72%. The incidence of hypotension was 39% in the S + C group versus 64% in the C group, and respiratory depression was 17% versus 16%, with no significant differences.