The negative effect of poverty on children's cognitive development has been proven, but few studies have examined the potential role of perceived poverty discrimination on poor children's cognitive development. This study investigated the effect of perceived discrimination on executive function, the mediating effect of self-esteem and the moderating effect of perceived social support among 711 children aged 8-13 (M = 9.97 years, SD = 1.19 years, girls: 48.80%) from a Chinese impoverished county. The results indicated that (1) perceived discrimination was negatively associated with children's executive function; (2) self-esteem partially mediated this association; and (3) perceived social support moderated the relation between perceived discrimination and children's self-esteem: high levels of perceived social support increased self-esteem for poor children with more perceived discrimination. The results suggested that self-esteem is a mechanism underlying the negative association between perceived discrimination and children's executive function and perceived social support plays a protective moderating role.