【Abstract】: Objective To investigate the characteristics of echocardiography of aortopulmonary septal defect (APSD) in order to improve the detection rate and diagnostic accuracy of noninvasive echocardiography for APSD. Methods The retrospective analysis of the characteristics of echocardiography APSD of Beijing Anzhen Hospital from 2002 to 2017 were confirmed by cardiac catheterization and operation results, it includes the type, location, size, shunt, merging other cardiac malformation of APSD. Results 1. 49 APSD was confirmed by cardiac catheterization and surgery, 45 cases were diagnosed by preoperative echocardiography, and 4 cases were missed, and the missed diagnosis rate was 8.2%. 2.Type I were 11 cases (22.4%), type II were 24 cases (49%), type III were14 cases (28.6%). All the 45 cases of echocardiography were consistent with the pathologic results. There were 4 cases (8.2%) of pure APSD (8.2%), and 45 cases (91.8%) were combined of other cardiac malformations, such as VSD. 3. Two-dimensional echocardiography: direct sign: APSD continuity interruption( 5mm-50mm). Second changes: the left heart system enlarged were 22 cases (44.9%), the right heart system enlarged were 4 cases (8.2%), the whole heart expanded (the left heart was) were 21 cases (42.9%), and the right ventricular wall thickened were 4 cases (8.2%). The inner diameter of the aorta and pulmonary artery was widened, especially the pulmonary artery. Color doppler flow imaging: left to right shunt :12 cases (26.7%), bi-directional shunt:25 cases (55.6%), and right to left shunt: 8 cases (17.7%). There were 3 cases of mild pulmonary hypertension (6.1%), 10 cases of moderate pulmonary hypertension (20.4%), and 36 cases of severe pulmonary hypertension (73.5%). 4. In the 45 cases of APSD diagnosed by ultrasonography, the median age of right-left shunt (Eisenmenger Syndrome) was 2.54 years. Conclusion Ultrasonography is an effective method for diagnosis of APSD. However, there is a missed diagnosis, and when there is intracardiac shunt, the possibility of APSD should be considered when there is no matching with pulmonary hypertension. The preoperative detailed evaluation of APSD is helpful to the formulation of clinical treatment strategy.