Research on the effects of the home literacy environment (HLE) on the literacy development of children with intellectual disabilities (ID) is limited, and relevant results are inconsistent. This study aimed to explore the influence of the HLE on the literacy development of children with ID, and the role of the reading interest and parent-child relationship in this process. The subjects of this study were 381 children with ID from special needs schools in 7 regions of China, including 234 boys and 147 girls aged 6-15 years. This study adopted the network survey method, and parents of these children completed the surveys of the HLE, literacy development, reading interest, and parent-child relationship. The results revealed that the HLE significantly influenced the literacy development of children with ID, and the reading interest partially mediated this effect. In this mediating process, the regression relationship between the HLE and the reading interest was positively regulated by the parent-child relationship. This study suggests that improving the HLE and parent-child relationship is beneficial for the reading interest and literacy development of children with ID.