Objective To investigate the value of index of consciousness （IoC） in predicting the sedation depth in infants and children with different doses of intranasal dexmedetomidine during echocardiography. Methods A total of 254 children patients with non ⁃ cyanotic congenital heart disease undergoing transthoracic echocardiography were divided into group A（intranasal dexmedetomidine 3 μg/kg，n = 127）and group B（intranasal dexmedetomidine 4 μg/kg，n = 127）. And IoC values were monitored before sedation（T0），before examination （T1），during examination（T2），after examination（T3），and when leaving the room（T4）. Correlation analysis and receiver⁃operating characteristic（ROC）curve were used to analyze the predictive value of IoC，The University of Michigan Sedation Scale（UMSS）score，body movement score and behavior score for the sedation depth，and the area under the ROC curve was calculated. Results The sedation success rate in group B was significantly higher than that in group A（P < 0.05）. The IoC value at T1，T2，T3 in group B was significantly lower than that in group A （P < 0.05）. Correlation analysis showed that IoC value was negatively correlated with UMSS score（r = -0.792， P < 0.01），but positively with behavior score（r = 0.429，P < 0.01）. ROC analysis showed that IoC had a better predictive value for sedation depth than other monitoring indicators. Conclusion Compared with sedation score and behavior score，IoC has better predictive value for the depth of sedation in infant and children echocardiography.