Abstract: Objective To observe the sedative effect of dexmedetomidine on pediatriac patients when extubating after cardiopulmonary bypass cardiac surgery. Methods From May 2013 to April 2015, a total of 127 pediatric patients were enrolled in this study.The patients were divided into two groups according to whether sedation with dexmedetomedine was lasted over extubation.Dexmedetomedine was continuously administered over the extubation period in observation group (n=74), and the patients were extubated without sedation in control group (n=53).The heart rate, mean arterial pressure and respiratory rate before, during and 10 min after extubation were recorded.Score of agitation scale before extubation, re-administration of sedative medication, duration of extubation time and intubation duration were also collected. Results There was no significant difference in heart rate (92.6±15.31) /min vs (91.72±16.52) /min, mean arterial pressure (68.52±6.43) mmHg vs (69.23±7.12) mmHg and respiratory rate (23.83±3.34) /min vs (24.17±3.52) /min during extubation between two groups (P> 0.05).The heart rate (94.32±14.23) /min vs (109.40±24.78) /min, (95.52±15.48) /min vs (104.62±23.37) /min, mean arterial pressure (67.47±5.69) mmHg vs (76.84±9.78) mmHg, (68.45±6.14) mmHg vs (74.19±8.67) mmHg and respiratory rate (24.25±3.86)/ min vs (27.36±5.48) /min, (23.94±4.15) /min vs (26.53±6.27) /min before and after extubation in observation group were significantly lower than control group (P< 0.05).The Agitation Ricker score (2.81±0.24) vs (3.92±0.53) and the incidence of re-administration of sedative medication (6.75% vs 39.62%) in observation group were significantly lower than control group (P< 0.05).The extubation time (47.32±11.24) min vs (58.46±25.03) min and intubation period (5.12±1.05) h vs (6.73±1.87) h in observation group were significantly lower than control group (P< 0.05). Conclusion Administration of dexmedetomedine over extubation after cardiac surgery with cardiopulmonary bypass can maintain steady hemodynamics, reduce agitation and avoid readministration of sedative medication in children, which will shorten the extubation time and intubation period effectively.