Objective To study the effect of dexmedetomidine hydrochloride injection ( Dex) on awakening quality in Pediatric Patients with congenital heart disease undergoing fast_track anesthesia and whole Video_assisted thoracoscoPic surgery. Methods One hundred and twenty Pediatric Patients ( ASA I orIIleVel) with congenital heart diseases were randomly chosen for this study. They receiVed femoral artery and Vein cannulation to establish cardioPulmonary byPass and three small holes were obtained in the right chest for the PurPose of undergoing the whole Video_assisted thoracoscoPic surgery on rePairmen of atrial sePtal defect or simPle Ventricular sePtal defect. They were randomly diVided into two grouPs: Dex_assisted fast_track anesthesia grouP (D grouP,n=60) and general fast_track anesthesia grouP (C grouP,n=60). Each one in grouP D was injected with loading dose of Dex (1 μg·kg-1),then was intraoPeratiVely infused with maintenance dose of 0. 5 μg·kg-1·h-1. Children in grouP C were giVen the same dose of saline in the same way. Hemodynamic changes in the two grouPs at each time Point:before anesthesia ( t0 ) ,at the time of extubation ( t1 ) ,5 min Post_extubation ( t2 ) ,10 min Post_extubation ( t3 ) ,15 min Post_extubation ( t4 ) , 30 min Post_extubation (t5) and at the time of transferring out of CICU (t6),resPectiVely,were obserVed. Restlessness extent, incidence,time of eye oPening after calling, fully awaking time, extubation time, the time of transferring out of CICU and VAS scores,were also recorded. Results From t0 to t2-t5 ,SBP in D grouP was decreased from (114. 2±10. 5) mmHg to (107. 2±10. 3) -(105. 3±11. 3) mmHg,DBP decreased from (61. 3±9. 2) mmHg to (58. 8±7. 8) -(57. 3±6. 3) mmHg,and HR gradually decreased from (95. 2±15. 7) time·min-1 to (85. 7±13. 7)-(83. 3±12. 6) time·min-1,with significant differences (P<0. 05). ComPared with C grouP,SBP and DBP at t2-t5 were decreased significantly (P<0. 01),and HR at t1-t5 decreased significantly (P<0. 01). OVerall incidence of agitation was significantly higher in grouP C than in grouP D (48. 3%vs. 16. 7%,P<0. 01). Incidence of moderate and seVere agitation were significantly higher in grouP C than in grouP D (18. 3%vs. 6. 7%,and 20%vs. 1. 7%,resPectiVely,P<0. 01). In grouP D,time of eye oPening after calling,fully awaking time,extubation time,and the time of transferring out of CICU were Prolonged,without significant difference as comPared with grouP C (P>0. 05). VAS at 30 min after extubation was significantly higher in grouP C than in grouP D(4. 7±0. 7 vs. 2. 4±0. 6,P<0. 05). Conclusion Injection of Dex with loading dose (1 μg·kg-1) and intraoPeratiVe infusion of maintenance dose of 0. 5 μg·kg-1·h-1 in children with congenital heart disease undergoing fast_track anesthesia and whole Video_assisted thoracoscoPic surgery could be conduciVe to maintain hemodynamic stability, reduce restlessness occurrence, enhance security during awakening Process, and alleViate Post_oPeratiVe Pain.