Objective To explore the relationship between the single umbilical artery (SUA) and cardiac defects and the necessity of routinely conducting fetal echocardiography for fetuses with SUA. Methods The routine fetal echocardiography was performed for 666 singleton pregnancies with high risk of fetal congenital heart disease (CHD) from September, 2009 to September, 2012. The sequential segmental analysis method was used to scan cardiac planes and to analyze and evaluate the position, major structures, and connections of the fetal heart. All cases were divided into the isolated SUA group (group A, n=63), SUA with other high risk factors of CHD group (group B, n=15), and non-SUA with other high risk factors of CHD group (group C, n=588). The echocardiography was performed for all fetuses after they were born for one month. The cardiac defects of three groups were analyzed and compared. Results The incidences of cardiac defects of three groups were 9.5% (6/63), 40.0% (6/15), and 3.9% (23/588), respectively. The results of statistical analysis showed that the incidence of cardiac defects of group B was significantly higher than that of other two groups and the incidence of cardiac defects of group A was significantly higher than that of group C. The differences were statistically significant (P<0.05). Conclusion The incidence of CHD of fetuses with SUA is extremely high. The routine fetal echocardiography is necessary for fetuses with SUA, especially for those associated with other high risk factors of CHD.