A 25-year-old woman, gravida 1, para 0, conceived dichorionic diamniotic twin pregnancy spontaneously. The couple was not consanguineous and had no reported history of medication, hereditary disease, substance abuse, or a family history of congenital anomalies and teratoma. The patient’s serology was negative for human immunodeficiency virus (HIV), venereal disease research laboratory (VDRL), and hepatitis B surface antigen (HBsAg) and she had no diabetes mellitus. During a routine second trimester ultrasound at 23 + 3 weeks’ gestation, a 3.2 cm mixed solid and cystic SCT starting from the sacral area was detected in one twin (twin B) with no other fetal abnormalities,and co-twin (twin A) with no abnormality. Given this condition, the patient was transferred to our department. The couple was extensively counseled by the multidisciplinary team regarding the diagnosis, treatment, and prognosis of the SCT twin. The parents refused to perform the fetal Magnetic Resonance Imaging(MRI) and examine the chromosome of both twins.The family opted to continue the pregnancy and the fetuses were followed closely. The gradual growth of the SCT mass was identified by sonography with no signs of hydrops and fetal cardiac failure. At 34 + 4 weeks’ gestation, on follow-up ultrasound, the fetus was detected with polyhydramnios and no signs of hydrops and the solid and cystic mass 6.3 × 2.7 × 2.9 cm.Planned cesarean section was performed at 37 weeks and 1 day. The healthy male co-twin (twin A) weighed 2880 g with Apgar scores of 10 and 10 at 1 and 5 minutes, respectively. The male twin with SCT (twin B) weighed 2900 g with Apgar scores of 10 and 10 at 1 and 5 minutes, respectively, complying with 6 × 3 × 3 cm cystic and solid mass in sacrococcygeal region.The neonate transferred to NICU due to SCT. At two days of age, Magnetic Resonance Imaging (MRI) was performed and showed: The sacrococcygeal region occupied by a cystic mass about 5.9 × 2.6 × 3.0 cm, which partly located behind the presacral peritoneum, the upper margin to the superior margin of sacral 3, the lower margin to the inferior margin of the caudal vertebra about 2.6 cm, boundary was not clear, the larger cystic focus is located in the presacral region, and the size is about 2.0 × 3.2 × 1.8 cm, a little T1WI and T2WI high signal can be found inside. The mass pushed the anorectal, rectum to the right front. The anal canal and sacral canal were not suffered. At four days of age, giant sacrococcygeal teratoma resection, coccyx resection, pelvic floor reconstruction and skin flap plasty were performed. The excision of the coccyx and mass was complete.The histopathology showed mature sacrococcygeal teratoma with negative margins. The baby discharged 7 days after surgery. Both babies and the mother were followed up. At age of 3 months, the baby with SCT removed was evaluated by ultrasonography and no abnormalities in sacrococcygeal region, with no uncontrolled urination, difficult bladder emptying, pyelonephritis and constipation.Both babies are in normal development until now. The flow diagram of this case is shown in in Fig..