Objective To analyze the diagnostic effect and application value of echocardiography in children with complex congenital heart disease（CCHD）. Methods A total of 50 children with complex congenital heart disease treated in our hospital from June 2017 to June 2020 were collected as study subjects. All children underwent echocardiography（UGG） and multi-slice spiral CT（MSCT）

and the imaging manifestations of the two groups were observed according to the pathological results of surgery

and the detection rates of intracardiac and extracardiac malformations were compared. Results The results of surgical pathology in 50 children showed that there were 142 cardiac malformations

including 72 intracardiac malformations and 70 extracardiac malformations. The diagnostic coincidence rate of intracardiac malformation was 98.57% compared with UCG and 80.56% with MSCT

and the difference was statistically significant（p<0.05）. The diagnostic coincidence rate of extracardiac malformation was 78.57% compared with UCG and 95.71% with MSCT

and the difference was statistically significant（p<0.05）.Conclusions In the diagnosis of complex congenital heart disease in children

echocardiography and multi-slice spiral CT have advantages

but there are some shortcomings. Therefore

in clinic

combined examination can be used to improve the diagnostic accuracy.