Objective To observe the effect of dexmedetomidine on off-pump coronary artery bypass grafting under fast track anesthesia. Methods 80 patients undergoing off-pump coronary artery bypass grafting(OPCABG) were randomly divided into control group (group C) and dexmedetomidine group (group D), with 40 cases in each group. In group D, 0.6μg/kg of dexmedetomidine was given 15 minutes before anesthesia induction. Then 0.5 μg/kg•h of dexmedetomidine was pumped until the sternum been closed. In group C, the equal volume of 0.9% sodium chloride was used. The heart rate (HR) and mean arterial pressure (MAP) were measured at T0 (15 minutes before anesthesia induction), T1 (5 minutes after injection of dextromethoridine or 0.9% sodium chloride), T2 (immediately after tracheal intubation), T3 (at the beginning of operation), T4 (the time of cleaving the sternum), T5 (before anastomosis of the first vessel), T6 (after anastomosis of the last vessel), T7 (the sternum was closed). The dosage of phenylephrine, nitroglycerin and atropine in the two groups were recorded. The extubation time, ICU stay time were recorded. Visual analogy score (VAS) was used to analyze the pain scores of 8h and 24h after operation. The incidence of hypotension, bradycardia, nausea and vomiting were analyzed within 24 hours after operation. Results There was no significant difference in HR and MAP between the two groups at T0 (P0.05). Compared with T0, the HR of T1, T3, T4, T5, T6 and T7 in group D were significantly reduced. The MAP of T5, T6,and T7 in both groups was significantly lower (P0.05). Compared with group C, the HR of T1, T2, T3, T4, T5, T6 and T7 in group D was significantly reduced (P0.05). The MAP of two groups at each time point has not significantly difference (P0.05). There was no significant difference in the use of noradrenaline and nitroglycerin between the two groups (P0.05). Compared with group C, the dosage of atropine in group D increased significantly (P0.05). There was no significant difference in extubation time, ICU stay time and 24h pain score after operation between the two groups (P0.05). The VAS score of group D was significantly lower than that of group C (P0.05). Conclusion Dexmedetomidine can stabilize hemodynamics and provide good postoperative analgesia for OPCABG under fast track cardiac anesthesia.