Objective Evaluate the preoperative clinical value of optimized low-doses CTA examination in children with congenital heart disease (CHD). Methods 139 children with CHD(aged 1 day-6 years) were included in this study, CTA examinations based on 3 different techniques including the front door and high-level mixed iterative reconstruction technique (iDose4), the front door and filter back projection reconstruction place place (FBP) and gate control and FBP were carried out on these children according to the patient's clinical visiting time. Statistical analysis including the analysis of variance and Post Hoc-two sample T test were performed to compare the effective radiation dose and image quality. The results of surgery were taken as the diagnostic criteria, and consistency analysis were used to evaluate the CTA diagnosis and echocardiography (UCG) diagnosis respectively. Results 1.Results on effective radiation dose: the front door iDose4 control group was 13.8% lower than the front door place control FBP group, the front control iDose4 place was 23.5% lower than a non-gate control FBP group (P<0.05).2. Results on image quality assessment: the front door place controlled iDose4 group, the front door FBP group place, non-gate control FBP respectively: Ⅲ level 36, 57, 12 cases, ⅡLevel 0, 25, 8 cases (χ2 =15, 879, P<0.05).3. Results on the consistency with surgical results: 102 children were carried out the surgical treatments, consistencies of preoperative CTA and UCG diagnosis were as follows: CTA total diagnostic coincidence rate 94.5% (P<0.001), the UCG diagnosis coincidence rate 90.4% (P<0.001). Conclusion Low doses of front door control iDose4 CTA technology has important preoperative clinical significance in children with CHD.