Ｏｂｊｅｃｔｉｖｅ　To research the appropriate dose of dexmedetomidine（Dex） in the anesthesia of the brain functional epilepsy resection， which does not affect the electroencephalogram and the electrophysiological monitoring situation.　Methods　Sixty patients with ASAⅠ-Ⅱ selective cerebral functional area surgery， male 34 cases， female 26 cases， ages 18 to 45 years old， 40 kg-74 kg weight. Using the random number table method， divided into four groups （n=15）. The control group （group C）， the Dex group intravenous injection respectively 0.25 μg·kg-1·h-1（group D1）， 0.50 μg·kg-1·h-1（group D2）， 1.00 μg·kg-1·h-1（group D3）. Three groups of intravenous loading doses within 15 min. And then respectively with the rate 0.25， 0.50 μg·kg-1·h-1 or 1.00 μg·kg?蛳1·h?蛳1 until the end of surgery by intravenous infusion. Record the electroencephalogram and electrophysiological monitoring of the situation， the dosage of propofol， recovery times， the value of BIS， the changes of blood pressure， heart rate and the occurrence of adverse reactions intraoperative.　Results　Compared with group C， the BIS value of group D1， D2 and D3 had been significantly decreased（P<0.05）. The ECoG amplitude of group C was higher， the inclusion of the interference wave was more， sometimes propofol caused the outbreak of the inhibition； the ECoG amplitude of group D3 was obviously lower； the ECoG amplitude of group D1 and D2 were moderate.　Conclusions　The adaptive dose range of the brain function lesion resection in patients with epilepsy in anesthesia appropriate ECoG and electrophysiological monitoring is 0.25 μg·kg-1·h-1 and 0.50 μg·kg-1·h-1. It is more suitable for the brain functional areas location of focal epilepsy surgery anesthesia.