The role of peer effects in children's human capital accumulation has attracted increased amounts of attention. Using data from a nationally representative survey of Chinese middle school students, this paper exploits random student-classroom assignment as a quasi-natural experiment to identify the peer effects of local students on the human capital of migrant children in Chinese middle schools. The results indicate that the peer effects of local students significantly improve the human capital of migrant children, including academic performance, cognitive abilities and non-cognitive abilities. Moreover, these peer effects can be further explained by improved parent-child relationships and parental expectations, increased student effort and expectations, and optimized teachers' teaching and school climate. Additionally, the peer effects from local students varies with migrant children's gender, Hukou, number of siblings and grade. Our research contributes to complementing the research field regarding peer effects and provides a new policy-oriented direction for the development of migrant children's human capital.