The inverse association between sibship size and education is well established in social research. The resource dilution model posits that under the assumption of finite education resources, additional children could dilute the quantity of educational resources any one child would receive, and thus exert negative impacts on children’s educational outcomes. In China, relevant researches are all based upon adult samples. As most of adults have ended their educational career, research with adult samples cannot examine the role that various educational resources play in explaining the negative link between sibship size and educational outcomes. In this paper, based on a children sample from 2010 China Family Panel Studies, we divide educational resources that might be influential for children’s education into three types: financial investment resources, parental involvement resources, and family environment resources. Our results reconfirm that children with bigger sibship sizes are more disadvantaged both in obtaining all these educational resources and in academic achievement. Moreover, we find these educational resources could help explain substantively the negative effect of sibship size on academic achievement, whereas the three types of educational resources contribute differently to explaining the effect of sibship size on word verbal skills and the effect of sibship size on math skills.