Background: Dexmedetomidine (DEX) is a highly selective 2-adrenergic receptor agonist with significant analgesia affection. This study is planned to explore the brain regions and functional neuronal network involved in promoting analgesia of Dexmedetomidine. Methods: Select 12 patients with the proposed intraoperative MR-guided radiofrequency ablation of epilepsy. The subjects were randomized into the Dexmedetomidine group (DEX group) (n=6) and the Opioid group (OPI group) (n=6). DEX group: continuous intravenously administered 1.5 µg kg-1 h-1 dexmedetomidine 15min before anesthesia induction, continuous infusion for 15min after anesthesia induction, and then Intraoperative functional magnetic resonance imaging scanning was started. OPI group: the equivalent administered speed 0.9% sodium chloride was continuously pumped for 15min before anesthesia induction, then induce and intraoperative fMRI scanning started after continuous 30min infusion. The intraoperative fMIR scan results were compared and analyzed to find the unique analgesic brain regions of DEX, and the differences of the functional neuronal network of analgesia effect between the two groups.