Peer contagion mainly involves bidirectional interactive processes, selectioneffect is the precondition of peer contagion, and socialization effect is the cause of negative influence of peer contagion on children's adjustment. The manifestation of peer contagion mainly includes two forms: externalization contagion and internalization contagion. At present, the explanation of the mechanism of peer contagion mainly involves five viewpoints: the viewpoint of social learning theory, the viewpoint of interpersonal theory, the viewpoint of social comparison theory, the viewpoint of group susceptibility theory and the viewpoint of biology. In the future, researchers can focus on the moderating factors of peer contagion and provide theoretical support for the intervention and prevention of peer contagion.