The avulsion fracture of calcaneal apophysis by Achilles tendon in children is quite rare. It may occur with the injury of the apophysis on the calcaneal tuberosity in the children below the age of 12 to 15 before the union of the apophysis. The authors surgically treated a 14-year-old gymnast with the avulsion fracture of the calcaneal tuberosity who injured at the landing of the floor exercise. Radiographs at the fourteen months of follow-up showed slight irregularity of the calcaneal tuberosity but there were no pain or limitation of activity. We report a case with the review of literatures.