Since the implementation of the “three-child policy” in 2021, China has entered a stage of supporting procreation. The number of multi-child families will keep increasing, and the new family relationship of siblings has reemerged in Chinese families. The interaction among siblings constitutes a part of children’s socialization. According to the theories of social learning and family systems, in the process of interacting with their siblings, children can internalize and form their own behavioral norms by observing and imitating the behaviors of their siblings. Through a review of the existing literature, it has been discovered that the factors influencing sibling relationships mainly include intrinsic factors (age, sibling structure, and temperament type) and family factors (parent-child relationships, marital relationships, and parenting styles), among which family factors are more significant. In the future, indepth exploration can be conducted on the influence of other aspects within the family system (such as filial piety and cultural traditions) on sibling relationships.