Lin, female, 5 months, 180226, from Anhui, had a giant abdominal teratoma with dilated cardiomyopathy and phenylketonuria. Cardiac function was very poor, with an EF of approximately 29.1%. After admission, cardiac function was adjusted and a retroperitoneal giant teratoma was resected. Postoperative pathology showed a mature teratoma. The tumor was 17*14*9cm with multinodular surface, smoother, cystic solidity in the cut surface, cystic area with multiple separated cystic cavities, maximum diameter 14cm, and yellow fluid in the content. The parenchymal area was 14*8cm, with bone, cartilage, fat and skin visible in the section, and no obvious area of hemorrhage and necrosis was seen. The tumor tissue was maturely differentiated and neuroglial tissue was seen. Adrenal tissue was also seen. After surgical resection of the tumor, the dilated cardiomyopathy gradually improved, and the cardiac function gradually returned to normal, and the EF value was about 68.1% at the 3-month postoperative review.