Objective: To investigate the effects of different effect compartment of sufentanil combined with propofol by target controlled infusion on Narcotrend index. Methods: 60 patients, aged 40~60, weight index<30 kg/m2, ASAⅠ-Ⅱ undergoing general anesthesia were randomly divided into 4 groups (n=15): sufentanil effect compartment concentration 0.1 ng/m L (group A), 0.2 ng/mL (group B), 0.3 ngmL (group C), and 0.4 ng/mL (group D). The propofol of 1.0 mg/kg was administered after 5 min when the concentration of sufentanil reached the effect compartment concentration. The parameters of BP, HR, SpO2 and Narcotrend index(NI) were recorded during proceeding of experiments. After experiments, all of patients were adjusted to appropriate anesthesia depth, then the muscle relaxants were administered and the tracheal intubations were done. Results: The NI decreased in varying degree with target injection of sufentanil, accompanied with the increase of target concentration, the trend of decrease is more obvious. During target-controlled infusion of sufentanil as sole, there was a negative correlation between the effect compartment concentration and NI, and the correlation index is-0.456. After 1 min of injecting propofol, the NI of Group D ascended initially, with statistical significance in comparison among groups (P<0.05), then the NI1 was decreased with the time. Conclusion: Sufentanil can decrease the NI, and the correlation between the effect compartment concentration and NI is negative, while sufentanil of 0.4 ng/m L effect compartment concentration combined with propofol caused the phenomenon that the NI raised temporarily, whereafter decreased. [ABSTRACT FROM AUTHOR]