The purpose of this study was to investigation of the role of Affects and metacognitive beliefs in prediction of youth self-harm behaviors. In a correlational descriptive design, 160 participants were selected using an available sampling method among dormitory students of Alzahra University and Tehran University. The data collection tools were metacognition questionnaire, positive and negative experience scale and self- harm questionnaire. The results showed that there was a significant negative correlation between positive affection and self- harm and also there was a significant positive correlation between negative emotion, uncontrollability and danger of thoughts, and cognitive trust with self-harm behaviors. The results of regression showed that the predictive variables of the present study were able to explain 22/1 percent of the changes in the variable of self-harm behaviors. The components of positive affection and metacognitive beliefs of uncontrollability and danger of thoughts had the highest importance in predicting of self-harm behaviors respectively.based on results of this study can be said that the reduction of pleasant emotional experiences and the lack of adaptive exposure with unpleasant emotional experiences, can lead people who have incompatible meta-cognitive beliefs toward self-harm behaviors.