Abstract: To explore the development of a standard closed fracture in rat tibia, a modi-fied apparatus was designed and tested on 62 female SD rats. The tibia was treated with an intramedullary Steinmann’s pin and then was fractured by the apparatus. The frac-ture type and displacement was observed by X-ray and the fracture healing was detected histologically. The fractures were transverse or transverse with a small oblique compo-nent in 92 cases with the success rate 74.2%. Histologically the fracture was healed in secondary. The closed fracture model of rat tibia made by the apparatus is highly repro-ducible,easy to make，and is a standard model.