Objective To compare the image quality, dose, diagnostic value of perspective ECG-triggering and restrospective ECG gating coronary artery computed tomography. Methods Retrospective analysis of 76 cases of congenital heart disease, which was confirmed by surgery, all patients in our hospital MSCT cardiac imaging, and record the patients' heart rate, scan time, effective dose. Line of prospective heart switch controlled switch and a retrospective heart MSCT imaging all the 38 cases of heart. 76 patients were confirmed by surgery and preoperative via after sternal cardiac ultrasound (TTE) examination. The image quality of all cardiac CTA images evaluated by two high qualification radiologists by double blind method, classification of quantitative criteria refer to five tables, evaluation content includes the overall image quality, opening heart cavity structure, coronary artery, coronary artery and the mainpulmonary artery showed. Results 76 cases of children were successfully completed the scan, 76 cases of children with cardiac structure, extravascular large blood vessels, coronary artery opening and trunk can clearly show that the prospective ECG gating group of effective dose and scan time And there was significant difference compared with retrospective ECG gated group (P<0.05). The mean effective dose of the prospective ECG gated group was about 76.21% lower than the retrospective ECG gated group. Conclusion MSCT prospective ECG gated cardiac imaging is superior to retrospective ECG under the premise of ensuring image quality. It should be the first choice for MSCT in children with congenital heart disease.