The present study aims to explore the associations between food insecurity and school performance, and the serial mediation of depression and educational expectation on the focal association, among Chinese rural left-behind children. This study conducted a cross-sectional survey on 2128 students (Grades 5-9, mean age = 13.21 years) who reported one or both parents had migrated into the urban sector. They responded to questions on school performance, educational expectation, The Food Insecurity Experience Scale, and The Birleson Depression Self-Rating Scale. Serial mediation modelling was used to test the mediating role of depression and educational expectation. It is found that food insecurity was significantly associated with school performance. Moreover, depression and educational expectation functioned as serial mediators and were fully mediating the association between food insecurity and school performance. The findings as with the severity of childhood food insecurity in rural China as well as its association with the negative consequences in children's education provide empirical support for contentions that food insecurity problem should be taken into account in designing and implementing school-based intervention programs for left-behind children. Moreover, schools shall pay special attention to the mental health risks of food insecurity among rural left-behind children.