Supracondylar fractures of the humerus are common in children, accounting for 3% to 1 8% of fractures in children and 60% of fractures of the elbow joint in children. Treatment: Gartland type I fracture: elbow joint flexion at 90° in a tubular cast for 3 weeks. The function of elbow joint movement can be restored naturally; Type II fracture: can be treated as Type I fracture with braking in the flexed elbow position. If bone insertion is found, inversion greater than 5° or valgus greater than 10° should be repositioned under anesthesia and fixed by percutaneous needle penetration; Type III: closed repositioning with kyphosis pin fixation: 1 medial + 2 lateral kyphosis pins are recommended; after surgery, the elbow joint should be braked for 3 weeks with thick cotton pads and a long arm cast to maintain the elbow joint in neutral position. A fully displaced supracondylar humerus fracture can have many serious complications if treatment is delayed. For the treatment of completely displaced supracondylar humerus fractures in children, incisional reduction should not be the conventional first choice; closed reduction is an effective and reliable option; combined medial and lateral cross-pinning is satisfactory, and this surgical approach is more likely to obtain good reduction, short operation time and simple operation; it is less traumatic to the child, and early functional exercises can be performed after surgery to promote the recovery of elbow joint function, which has wide clinical value.