This study investigated the internal mechanism of the relationship between primary school students’ peer relationships and their performance in the Chinese language and literature. We constructed a chain mediation model, focused on the mediation effects of parental involvement and the sense of autonomy, on the correlation between peer relationships and performance in Chinese language scores. A questionnaire survey was conducted among 1,503 students in grades 4–6, and their parents, in three cities in Jiangsu Province. The result indicated the following: (1) there was a significant positive correlation between primary school students’ peer relationships, parental involvement, sense of autonomy, and the level of Chinese language scores; (2) parental involvement and the sense of autonomy, respectively, mediate the relationship between peer relationships and Chinese language scores; (3) primary school students’ parental involvement and sense of autonomy play a chain-like mediating role in the relationship between their peer relationships and Chinese language scores. The research results provide a reference for exploring the educational strategies of primary school students’ Chinese literacy.