The general condition, clinical and pathological characteristics, and treatment regimens of patients prenatally and postnatally diagnosed with congenital choledochal malformation (CM) were analyzed in order to investigate the clinical significance of early diagnosis, treatment, and intervention in CM. We retrospectively analyzed 33 children who were admitted to the Children’s Hospital of Soochow University between 1 March 2010 and 31 May 2019, and their diagnosis of CM was confirmed by radiological, surgical and pathological findings. All the patients were under 36 months of age. The patients were divided into prenatally diagnosed and postnatally diagnosed groups. There were 16 and 17 CM patients in the prenatally and postnatally diagnosed groups, respectively, with a preponderance of females in both groups. Compared with the prenatally diagnosed group, the postnatally diagnosed group had a higher incidence of abdominal pain and vomiting (p < 0.05) and higher AST, GGT, and TB levels (p < 0.05). Although postoperative histopathological examination showed inflammation in both groups, congestion in the cyst walls and fibrous tissue hyperplasia were more significant in the postnatally diagnosed group (p < 0.05). In addition, operation time, length of time required to resume a normal diet after surgery, and total length of hospitalization differed between the 2 groups (p < 0.05), with the prenatally diagnosed group having a relatively longer operation time and taking longer to resume a normal diet after surgery. However, the total length of hospitalization in the prenatally diagnosed group was shorter than that in the postnatally diagnosed group. Compared with prenatally diagnosed CM patients, more symptoms, greater severity of symptoms, and more time to recovery after surgery were observed in postnatally diagnosed CM patients.