Objective To evaluate the value of 64-slice multidetector computed tomography (MDCT) as a non-invasive diagnostic modality in the young children suspected with coronary artery aneurysm due to Kawasaki disease. method Twenty patients (mean age 4.0 years, range 0.6–7 years) with Kawasaki disease suspected with coronary artery aneurysm underwent 64-slice MDCT ECG-gated coronary angiography from 2007 to 2015. The data of twenty patients who were younger than 4 years old was acquired without breath holding. Two pediatric radiologists independently assessed image quality and the diameter of all coronary segments were measured. The number, position, shape and size of each coronary artery aneurysm were observed and compared with those of echocardiography (ECHO) performed previously. Results There is no significant difference in inter-observer and intra-observer. A total of 60 branches permitted visualization with diagnostic image quality. A total of 31 coronary artery aneurysms were identified. Ten tumors were small, fourteen were medium and seven were giant. The affected branches included 17/20 of LAD, 1/20 of LCX; 13/20 of RCA. Calci five stenotic segments were found. ECHO failed to detect 6 tumors in LAD, 1 in LCX and 2 in RCA, and those included 6 small aneurysms. Conclusion 64-slice MDCT is an useful modality for assessing young children with Kawasaki disease.