Objective To evaluate the outcome of using locking plate as a definitive external fixator at first stage for open tibialfractures of gustilo type ⅢA.Methods 19 cases Open Tibial Fractures of Gustilo Type ⅢA patients from the Second Affiliated Hospital of Inner Mongolia were included in the present study from January 2015 to June 2019.All the patients were treated with locking plate as a definitive external fixator at first stage.They were 12 males and 7 females with an average age of 43 years(from 25 to 61 years)．To evaluate the fracture healing time, alunion ,joint function ,deep infection，nail infection and according to the functional assessment by the Johner-Wruhs system at Last follow-up time.Results Eventually，all of the fractures united,no malunion,No loosening or failure of the external fixator,no cases of deep infection.The fracture healing time was 13 weeks（range 10 ～ 17 weeks）.Pin tract infection was seen in 1 patient.Local soft tissue necrosis was seen in 1 patient,who is caused by contusion before operation and take off scabs by no special treatment.According to the functional assessment by the Johner-Wruhs system，in which 13 cases were excellent，5 ease were good and 1 medium case,the excellent to good rate was 94.74%. Conclusion The locking plate used as a definitive external fixator at First Stage may be a useful therapeutic method for treating Open Tibial Fractures of Gustilo Type ⅢA.