Prior research has identified discrimination as a key risk factor of delinquency among migrant children. Few studies, however, have examined how discrimination is related to delinquency. Informed by the general strain theory (GST), discrimination likely generates negative emotions, fosters deviant peer association and erodes social bonds, and all of which significantly predict delinquency. Hence, it is hypothesized that negative emotions, deviant peer association, and social bonds mediate the relationship between discrimination and delinquency. The above mechanisms are not without condition. The recent extension of GST (EGST) suggests that some variables, such as social support, may have an effect on the process from strain to delinquency. Therefore, it is further hypothesized that social support moderates the effect of discrimination on delinquency To test these hypotheses, a two-wave survey of 1,300 students attending secondary schools designed for migrant children from one of the largest cities in southwest China was applied in the current study. To make a possible causal inference, explanatory variables were all measured in the first wave of the survey, and the key dependent variable —delinquency—was measured both in the first and the second wave of the survey. Structural equation modeling (SEM) analysis was conducted to test the direct and indirect effects of discrimination on delinquency with negative emotions, deviant peer association, and social bonds as mediators. SEM group comparison analysis was applied to investigate the moderating effect of social support. The findings from the current study were threefold: First, among four types of discrimination, policy discrimination was the most severe form perceived by migrant students. Second, discrimination was positively related to delinquency, but its effect iii was fully mediated by negative emotion, deviant peer association and social bonds. Third, social support played a moderating role in the relationship between discrimination and delinquency. The total effect of discrimination on delinquency was negatively associated with social support, nevertheless, the mechanism linking discrimination and delinquency varied by different levels of social support.