Objective To investigate the outcome of open reduction with K-wire or head-less screw internal fixation of humeral capitellum fracture in adolescent. Methods The data of all patients with coronal humeral capitellum fractures in our department from september , 2017 to april , 2020 were analyzed. There were 22 cases in total, including 19 males, 3 females, 11 cases on the left side and 11 cases on the right side. The youngest was 11 years old and the oldest was 15 years old. The average age was (13.47±1.31) years old. The time from injury to surgery was (2.61±1.32) days. All children were classified based on CT results before surgery. According to the Bryan-Morrey classification criteria, there were 12 cases of type Ⅰ and 10 cases of Ⅳ; according to the Boston classification of adolescents, they were all coronal shear type Ⅰb fractures. All patients underwent Kocher approach open reduction, 12 cases were fixed with K-wires, and 10 cases were fixed with head-less screw. The elbow joint function evaluation adopts Mayo standard and quick-DASH scoring standard. At the last follow-up, the humeral head necrosis and osteoarthritis were evaluated based on X-ray. Results All patients follow-up time ranged from 12 months to 48 months (mean 31.04±4.05 months). The patients were divided into two groups according to the internal fixation method. All patients had no recent complications such as superficial infection, K-wire shedding, and plaster pressure sores. The Mayo scoring criteria of the elbow joints were 95.51±1.17 and 94.62±3.31, the quick-DASH scores of the two groups were 14.00±10.24 and 16.89±13.62, respectively, and there were no significantly difference in both criteria. At the last follow-up, all patients had no complications such as nonunion, osteoarthritis, and capitellum necrosis. Conclusion The coronal shearing type of capitellum fractures mostly occur in adolescent, open reduction with K-wire or head-less screw was effective in short-term follow-up.