Objective To compare the efficacy and safety of intranasal dexmedetomidine (Dex) between different doses of 2.5 μg/kg and 3.0 μg/kg in pediatric echocardiography sedation, and to explore the factors affecting recovery. Methods One hundred and eleven children, aged 1 to 36 months, were divided into 2 groups according to the random number table method: Dex 2.5 μg/kg group received an intranasal dose of 2.5 μg/kg Dex (D1 group, n=57) and Dex 3.0 μg/kg group received an intranasal dose of 3.0 μg/kg (D2 group, n=54). The induction time and total sedation time were compared．The success rate of sedation, the occurrence of any side effects with the drug and vital signs were also compared. Using age, sex, weight, fasting time and onset time as independent variables and total sedation time as dependent variables， the multiple linear regression analysis was performed to filtrate and formulate the valuable factors influencing recovery time Results There was no significant difference in induction time between D1 and D2 groups (P>0.05). The total sedation time in D2 group was significantly longer than the time in D1 group (P<0.05). There was no statistically significant difference in sedation success rate and incidence of side effects between the two groups (P>0.05). Weight has a significant negative effect on total sedation time. The total sedation time at age≤12 months was longer than the time at age>12 months in both groups (P<0.05). Conclusions Compared with a dose of 3.0 μg/kg given intranasally, a dose of 2.5 μg/kg Dex can not only provide satisfactory sedation effect, but also shorten the length of hospital stay. The total sedation time was negatively correlated with weight. Age can be used as a reference for dosage. For infants under 1 year old, dosage should be determined according to the required length of sedation.