On March 23, 2010, we successfully treated a boy with synpolydactyly who had a total of 31 fingers and toes. Although there was bone syndactyly both the hands of the boy, one-step correction of four extremities was successful, this operation lasted 5 h and 20 min and intraoperative bleeding was about 50 ml. Skin grafting was successful after operation and all incisions healed well. The appearance and function of hands and feet were satisfactory.