Abstract: Objective: To compare the onset time, duration, relaxant depth and devagus nerve effect of rocuronium in three different doses undergoing balanced anesthesia. Methods: 60 cases divided randomly into 3 groups(20cases/group) were anesthetized with Midazolam 0.2mg/kg, Propofol 2.0mg/kg, Fentanyl 5μg/kg and rocuronium 0.6mg/kg (Ⅰ)0.9mg/kg(Ⅱ)50mg(Ⅲ)respectively. Tracheal intubations were performed by the TOF_GUARD monitoring.The onset time and the duration time were observed,also BP, P, ECG (devagus index) simultanelously.Results: The relaxant depth was excellent in all cases.No markedly cardiovascular effect was found compared with preinjection. The onset time is 110±12 9sec (Ⅰ)73±16 5sec,(Ⅱ)82±25sec, (Ⅲ)respectively and the druation time is 45±12 2min ,(Ⅰ)70±20.5min,(Ⅱ)58±18.6min,(Ⅲ)respectively. Conclusion: Rocuronium is a short-moderated non-depolarizing neuromuscular blocking. The onset is shortened and the duration is delayed when the dose is increased during 2-3ED95. No devagus nerve effec is found so much as the dose reaches to 0.9mg/kg. So 50mg Rocuronium (equal to 0 8±1 2mg/kg) is available in these cases provided with convenience practically.