Abstract: Objective To investigate epidemiological characteristics and factors influencing non ?suicidal self?injury（NSSI）behaviors among middle school students in Shenzhen and to provide scientific evidence for its intervention and prevention. Methods A stratified cluster sampling method was used to select middle school students from 10 schools in Shenzhen for questionnaire survey. The survey content in?cluded general conditions and injury behavior. A Chi?square test and logistic regression were used for data analysis. Results A total of 3 737 students，including 2 033 boys and 1 704 girls，were surveyed，and the ratio of males to females was 1.19∶1. The average age of the participants was 15 years old. In the past year，the prevalence rate of NSSI among middle school students in Shenzhen was 34.7%. Unconditional multivariate logistic analysis showed that the NSSI level of students aged 11-16 years was higher than that of the other age groups（OR＝1.220），the students with trauma had higher NSSI level than those without trauma（OR＝1.788），the NSSI level of students living on campus was lower than that of students not liv?ing on campus（OR＝0.724），and the incidence of NSSI among students with close friends was lower（OR＝0.804）. Conclusion s The prevalence rate of NSSI among middle school students in Shenzhen was high. Early detection of NSSI and interventions based on relevant influencing factors should be taken to re?duce and prevent the occurrence of NSSI.