Abstract:[Objective] To compare the clinical outcomes of external fixator versus plate internal fixation for humeral shaft fracture sec- ondary to hand grenade throwing. [Methods] A retrospective study was done on 60 patients who underwent surgical treatment for humeral shaft fracture secondary to hand grenade throwing from January 2016 to January 2020. According to the doctor-patient communication pre- operatively, 30 patients had the fracture fixed with an external fixator, if necessary, lag screws by a small incision were added (the EF group) , while the remaining 30 patients were treated with plate for internal fixation (the IF group) . The preoperative general data, periopera- tive conditions, follow-up results and imaging data of the two groups were compared. [Results] The intraoperative radial nerve injury hap- pened in 1 case of the EF group, while 6 cases of the IF group, which was statistically significant (P<0.05) . The EF group proved signifi- cantly superior to the IF group in terms of incision length and intraoperative blood loss (P<0.05) . During the follow-up lasted for (14.23± 1.89) months, the EF group resumed active activity and full weight-bearing activity significantly earlier than the IF group (P<0.05) . The el- bow flexion- extension range of motion (ROM) , shoulder forward lifting ROM, MEPS and Constant-Murley score improved gradually in both groups. The EF group was significantly superior to the IF group in elbow ROM and MEPS scores (P<0.05) , but there was no signifi- cant difference in shoulder ROM and Constant-Murley score between the two groups at 6 and 12 months postoperatively (P<0.05) . Radio- graphically, although no a significant difference in fracture reduction quality was found between the two groups (P>0.05) , the EF group had fracture healing on images significantly earlier than the IF group (P<0.05) . [Conclusion] Both external fixator and plate internal fixation are suitable techniques for the treatment of humeral shaft fracture secondary to hand grenade throwing. By comparison, the EF has the ad- vantages of minimizing surgical trauma, declining complications and earlier fractur healing.