Objective To investigate the preferred velocity and time point of injecting sufentanil and propofol for elderly patients undergoing gastroscopy. Methods A prospective study was carried out on 90 elderly patients (70 to 86 years old) with America Society of Anesthesiologist (ASA) score of Ⅰ?Ⅲ undergoing scheduled gastroscopy in our hospital from March 2013 to October 2014 were enrolled in this study. They were randomly allocated into 3 groups (n＝30 for each group), that is, V1, V2 and V3 groups, according to different administration velocities and time points of sufentanil and propofol. The concentrations of sufentanil and propofol were 1mg/L and 10g/L respectively. In 2min after injection of 0.1μg/kg sufentanil, the patients of V1 and V2 groups were administered with 1mg/kg propofol. Sufentanil and propofol were delivered at the speed of 1ml/10s and 1ml/8s respectively in both V1 and V2 groups. In 30s after loss of eyelash reflex (LER), the patients received injection of 10～20mg propofol. After receiving injection of 0.1μg/kg sufentanil, the patients in V3 group were administered 1mg/kg propofol immediately. The 2 drugs were delivered at a velocity of 1ml/5s. After LER, the gastroscopy began. A bolus of 10～20mg propofol was administered in case of body movement. Their mean arterial pressure (MAP), heart rate (HR) and oxyhemoglobin saturation (SpO2) were observed among 3 groups before medication (T1), 2min after medication (T2), immediately after gastroscopy (T3), and 10min after gastroscopy (T4). Induction time, propofol dosage, palinesthesia time, as well as incidence of body movement and respiratory depression during gastroscopy were recorded and compared among the 3 groups. Results There was no obvious difference in terms of ASA physical status, age, gender, body mass, gastroscopy time and departure time among the 3 groups (P＞0.05). At T2, MAP, HR and SpO2 were significantly higher in V1 and V2 groups than in V3 group (P＞0.05). And these indices were lower in the 3 groups at T2 than at T1, T3 and T4. Compared with the V3 group, V1 and V2 groups had a significantly longer induction time (P＜0.05), smaller dosage of propofol (P＜0.05), shorter palinesthesia time (P＜0.05), and lower incidences of body movement and respiratory depression (P＜0.05). But, no obvious difference was seen in the above parameters between V1 and V2 groups (P＞0.05). Conclusion Sufentanil injected at speed of 1ml/8?10s followed by 10?20mg propofol in 2min later at the same speed can provide safe and effective anesthesia for gastroscopy in the elderly patients.