Teratoma is a common germ cell tumor, which most cases can be diagnosed by imaging examination. At present, surgical treatment is the main treatment method, but the occurrence of teratoma in some cases brings lots of trouble. Our case was a 2-month-old baby boy with abdominal distension as main manifestation at the beginning, and was diagnosed by CT as a large mass in the left abdomen (teratoma). The mass adjoined closely to the pancreas and brought much complexity for surgical excision. We therefore share with our colleagues the surgical experience of this particular case. Surgical excision of intraperitoneal complex teratoma is the key to radical cure of the tumor.