Background: Unilateral bone cyst (UBC) is a common lesion in children. Currently, the commonly used treatment methods for UBC have the defects of large surgical trauma and high recurrence rate. Objective: To investigate the effect of elastic intramedullary nail in the treatment of long bone cyst in children with pathological fracture. Methods: 11 patients with pathological fracture long bone cyst were treated with elastic intramedullary nail. There are 7 men and 4 women. The age ranged from 6 to 12 years, with a mean age of 7.6 years. There were 3 cases of proximal humerus, 2 cases of middle humerus, 1 case of whole humerus, 2 cases of proximal femur, 1 case of middle femur, and 2 cases of middle tibia. Results: t test was performed on the remaining static penetration area of the cyst measured at two adjacent time points using SPSS25 statistical software. P < 0.05 was considered statistically significant. Results All the 11 patients were followed up for 4 to 24 months, with an average of 12 months. The cyst healed in 4 cases (36.3%), the defect healed in 4 cases (36.3%), the healing rate was 72.7%, and 3 cases were sustained (1 case was followed up for 4 months). Discussion: Minimally invasive elastic nail fixation is effective in the treatment of bone cyst. However, the limitations of this study are influenced by the duration of follow-up, which is still ongoing for some UBC children. Long-term elastic titanium intramedullary nail implantation in the treatment of long bone cyst has the characteristics of single intervention, small injury, good stability and prevention of pathological fracture.