Objective to examine three models relations among social support, self-concept and deliberate self-harm. Methods A total of 776 college students from a university in Jieyang were investigated by using the self-concept clarity scale, adapted from the Perceptive Social Support Scale (PSSS) and Intentional self-injury Questionnaire (DSHI) compiled by Zimet Results Both social support and self-concept clarity can effectively predict self-injury, with coefficient of determination (p<0.001) Social support can significantly predict self-concept (p<0.001) When self-concept clarity was added to the regression equation, the predictive effect of social support on self-injury decreased but was still significant (p<0.001); Regression analysis showed that social support had no significant predictive effect on high self-concept (p>0.05). The predictive effect of social support on low self-concept was significant (p<0.001). Conclusion: (1) Both social support and self-concept had protective effects on deliberate self-harm, which supported the additive effect model. (2) Self-concept had partial mediation effect on social support to deliberate selfharm, which supports the mediation effect model. (3) The protective effect of social support on deliberate self-harm was obvious in the low self-concept group, which belonged to the antagonistic interaction.