Objective : To estimate the prevalence and risk factors of suicide ideation,suicide planning and suicide attempts among middle school students and to provide reference for suicide intervention. Methods : The students of grade 7 to 12 in Ningbo were recruited through multi-stage random sampling method. A self-reported questionnaire survey was conducted to collect the information about suicide ideation,suicide planning and suicide attempts within 12 months. A multivariate logistic regression model was used to analyze the risk factors for the three aspects of suicide among middle school students. Results: A total of 10 729 questionnaires were sent out and 10 726 valid ones were collected,with a validity rate of 99.97%. The prevalence rates of suicide ideation,suicide planning and suicide attempts among middle school students during the last 12 months were 12.93%,4.54% and 5.06%,respectively. The results of multivariate logistic regression analysis indicated that females（OR：1.397-1.575,95%CI：1.178-1.927）,students of grade 7 to 9（OR：1.625-1.824,95%CI：1.323-2.082）,poor health condition（OR：1.160-2.131,95%CI：1.005-2.985）,loneliness（OR：1.574-4.423,95%CI：1.221-5.254 ）,desperation（OR：2.796-3.232,95%CI：2.400-3.990）,anxiety（OR：1.890-2.117,95%CI：1.503-2.496）,less than 8 hours a day of sleep（OR：1.152-1.263,95%CI：1.030-1.594）,smoking（OR：1.476-2.074,95%CI：1.055-3.072）,drinking（OR：1.479-1.863,95%CI：1.271-2.296）,fighting（OR：1.716-1.941,95%CI：1.330-2.422）and school bullying（OR：2.254-3.292,95%CI：1.342-5.277）were common risk factors for suicide ideation,suicide planning and suicide attempts;physical activity（OR：0.597-0.720,95%CI：0.474-0.923）was a common protective factor for suicide ideation,suicide planning and suicide attempts. Conclusion Females,lower grade,poor health condition,loneliness,desperation,anxiety,lack of sleep,smoking,drinking,fighting,school bullying and physical activity were influencing factors for suicidal behaviors.