Ｏｂｊｅｃｔｉｖｅ　To investigate the optimal dose of remifentanil combined with propofol in painless gastroscopy.　Methods　Aged 20－60 years old, ASA Ⅰ or Ⅱ, 300 cases of patients undergoing painless gastroscopy were randomly divided into three groups (n=100), group R1 (remifentanil 0.25 μg/kg), group R2 (remifentanil 0.5 μg/kg), group R3 (remifentanil 1.0 μg/kg). The values of BIS, MAP, HR, SpO2 were recorded in the time of pre-anesthesia (T0), gastroscope placement (T1) and gastroscope exit (T2), and other data were recorded including propofol dosage, assisted respiration, intraoperative body movement, gastroscopy time, recovery time, intraoperative awareness, nausea and vomiting, dizziness and time of departure from the hospital etc.　Results　There were no significant differences in the values of BIS, MAP, SpO2 among the three groups at T0, T1 and T2 (P>0.05). SpO2 of group R1[(96.9±2.1)%] and group R2 [(96.2±2.9)%] were higher than values of group R3 [(92.1±5.5)%]. At T1, the difference was statistically significant (P< 0.05), but there were no statistically significant between group R1 and group R2 at T1, and among the three groups at T2. The propofol dosage of group R1[(110±12) mg] and of group R2[(65±8) mg] were significantly higher than that in group R3 [(48±6) mg], the propofol dosage of group R1 also was significantly greater than that in group R2(P<0.05). Assisted respiration cases in group R1 (6%), group R2(9%) compared with group R3(21%) were obviously reduced, the difference was statistically significant (P<0.05). When group R1 was compared with group R2 and group R3, there were significantly prolonged or more at the recovery time, the time of departure from the hospital, intraoperative body movement, and dizziness, the difference was statistically significant(P<0.05), but there was no statistical significance between the R2 group and R3 group(P>0.05). There was no significant difference among the three groups of patients at intraoperative awareness, gastroscopy time, nausea and vomiting (P>0.05).　Conclusions　This study suggests that 0.5 μg/kg remifentanil assisted appropriate propofol is the most suitable solution for gastroscopy.