Background: Total anomalous pulmonary venous connection (TAPVC) is a serious congenital heart defect, and the accuracy of its diagnosis has a significant impact on surgical planning and prognosis. In this study, we systematically evaluated the feasibility of echocardiography combined with angiography in the diagnosis of abnormal locations of TAPVC. Methods: This retrospective cohort study aims to evaluate the clinical utility of echocardiography in the preoperative diagnosis of TAPVC in children. A total of 105 pediatric patients who underwent corrective TAPVC surgery at the Hunan Children's Hospital were included. A combined echocardiography, and CT angiography (CTA), diagnosis was compared. The effects of echocardiography and CTA on the type of TAPVC, the auxiliary diagnosis of cardiac malformations, and the details of TAPVC on surgery were evaluated separately. Results: The positive diagnosis rate of TAPVC after combined echocardiography and CTA was 100%, and the type of TAPVC was supracardiac in 46 cases, intracardiac in 33 cases, subcardiac in 14 cases, and mixed in 12 cases. The diagnostic rate of echocardiography was 82.86%, which was lower than that of CTA (94.29%). The combined diagnosis method had the highest diagnosis rate of 100% (p < 0.05). The correct recognition rate of echocardiography in the diagnosis of heart-related malformations (91.43%) was lower than that of CTA (97.14%), and the correct recognition rate of combined diagnosis was 100% (p < 0.05). Two independent cardiologists evaluated the imaging approach based on the clarity of the images, the level of detail, and their support for the surgical plan. There was no statistically significant difference between the two methods (p > 0.05). Conclusions: Echocardiography and CTA have high accuracy and clinical value in the preoperative diagnosis of TAPVC in children, respectively, and echocardiography combined with CTA plays an important role in the diagnosis of TAPVC, related cardiac malformations and preoperative evaluation, and the selection of imaging examination methods should be based on specific clinical conditions.