Abstract: Objective To explore the prevalent characteristics of non-suicidal self-injury among middle school students in mainland China,and to provide basic information for prevention and intervention.Methods The relevant studies,which reported the prevalence of non-suicidal self-injury in middle school students among mainland China,were systematically searched via electronic databases,including China Biological Medicine(CBM),China National Knowledge Infrastructure(CNKI),VIP database,Wanfang database,PubMed,Embase,and Web of science.Meta-analysis was conducted by using R software and its Meta packages.Subgroup analysis was conducted according to gender,senior/junior,urban/rural,whether was only child or not,the research region and the research year period,and sensitivity analysis and publication bias were performed.Results A total of 22 eligible studies,with 146 936 middle school students,were finally included.The pooled prevalence of non-suicidal self-injury was 27.4% (95%CI=24.5%-30.2%).Subgroup analysis of non-suicidal self-injury in Chinese middle school students showed that the pooled estimate of prevalence for male(27.2%) was higher than that in female(25.6%);the prevalence of more than one child(28.8%) was higher than that of only child(28.0%);rural middle school students(32.2%) was higher than in urban(27.7%);middle region (32.3%) was higher than eastern(25.4%),western(30.1%) and northeastern(5.5%) regions;research year period among 2012 and then (31.4%) was higher than before 2012(22.7%).All of those differences were statistically significant(x2 =237.03,9.85,39.28,531,58,120.95,P<0.05).No publication bias was found in the researched literature,and the results were robust.Conclusion The pooled prevalence of non-suicidal self-injury among middle school students in mainland China is quite high,and there are differences between gender,urban/rural,whether only child or not,the research region,and the research year period.