According to 73 patients with middle clavicle fracture treated conservatively, a new classification of middle clavicle fracture was proposed, and the clinical effect of plastic splint in the treatment of middle clavicle fracture was observed. Total 73 patients with middle clavicle fracture treated with plastic splint from September 2018 to August 2020 were analyzed retrospectively. All the patients were divided into 4 types according to the degree of fracture displacement. There were 16 cases of typeⅠ, including 7 males and 9 females, ranging in age from 18 to 37 years old, with a mean of (28.6±7.8) years old;12 cases of mild disease, 3 cases of moderate disease and 1 case of severe disease. There were 16 cases of type Ⅱ, including 6 males and 10 females, ranging in age from 25 to 49 years old, with a mean of (37.3±9.4) years old;5 cases of mild disease, 8 cases of moderate disease and 3 cases of severe disease. There were 7 cases of type Ⅲ, including 4 males and 3 females, ranging in age from 33 to 57 years old;2 cases of mild disease, 3 cases of moderate disease and 2 cases of severe disease. There were 34 cases of type Ⅳ, including 16 males and 18 females, ranging in age from 48 to 82 years old, with a mean of(66.4±14.9) years old;7 cases of mild disease, 17 cases of moderate disease and 10 cases of severe disease. All patients received plastic splint external fixation for 4 weeks. Visual analgue scale (VAS) and Constant-Murley shoulder scores before treatment and 1, 3 and 9 months after treatment were observed and recorded to evaluate the change of pain degree and shoulder function recovery before and after treatment. The patients' satisfaction with the appearance after treatment was recorded at the latest follow-up. The X-ray findings at the latest follow-up were used to judge whether the patient had fracture nonunion. And according to the fracture healing time and imaging findings, the excellent and good rate of clinical curative effect in patients with different types was obtained. All patients were followed up, and the duration ranged from 9 to 11 months, with a mean of (9.8±0.7) months. The VAS scores of typeⅠ, typeⅡand type Ⅳ before treatment were 2.88±0.83, 3.67±0.80 and 6.92±1.71 respectively, which were decreased to 0.54±0.19, 0.77±0.25 and 1.18±0.17 respectively after 9 months of treatment. The Constant-Murley shoulder scores of typeⅠ, typeⅡand type Ⅳ were 65.81±2.09, 63.50±2.22 and 47.93±2.91 respectively before treatment, and increased to 88.56±2.11, 85.12±2.23 and 71.25±2.16 respectively after 9 months of treatment. Five patients were not satisfied with the appearance after treatment;6 patients had no obvious continuous callus passing through after 9 months of treatment, which was fracture nonunion. The classification of middle clavicle fracture is more appropriate to the clinic, which has a certain clinical guiding significance for the selection of treatment methods and prognosis of middle clavicle fracture. Plastic splint is effective in the treatment of middle clavicle fracture without obvious displacement and overlapping displacement, and the incidence of complications is low. It can be popularized in clinic.