Objective: To explore the correlation between parent-child separation experience and non suicidal self injury (NSSI) behavior among junior and senior high school students, so as to provide a reference for the prevention and improvement of NSSI behavior among junior and senior high school students. Methods: Using a stratified cluster random sampling method, 3 114 junior and senior high school students aged 11-19 years were recruited from Chenzhou and Jishou cities in Hunan Province between November 2024 and September 2025. A self designed questionnaire and the Functional Self injury Behavior Assessment Scale were used to collect information on parental labor migration and adolescents NSSI behavior status. Binary Logistic regression model was used to analyse the association between parent-child separation experiences and NSSI behavior among junior and senior high school students, with further stratified analysis by gender. Results: The prevalence rate of NSSI behavior among junior and senior high school students was 9.9%, and the overall incidence of parent-child separation was 48.9%, comprising 17.1% separated from their father only, 5.5% separated from their mother only, and 26.3% separated from both parents. After adjusting for variables such as age, gender, and ethnicity, the results of binary Logistic regression analyses indicated that adolescents with parent-child separation experiences had a higher risk of NSSI behavior ( OR =1.31, 95% CI =1.01-1.69, P <0.05). Compared with those without parent-child separation experiences, adolescents who were separated from their mother only ( OR =1.68, 95% CI =1.03-2.74) or from both parents ( OR =1.41, 95% CI =1.04-1.92) showed significantly increased risks of NSSI behavior (both P <0.05). Conclusions Parent-child separation experiences are associated with an increased risk of NSSI behavior among junior and senior high school students. Strengthened attention should be paid to left behind senior high school students to reduce the occurrence of NSSI in adolescents.