Abstract: The obesity epidemic in children and adolescents has become more and more quickly,which is contrary to the target of "healthy China 2030".For the purpose, the research is to study the prevention program and the social diffusion phenomenon of obesity among young peoplethrough the literature analysis.The results are as follow,1) the social network of young people is a typical complex network, and conforms to the social network characteristics such as power law distribution, peer effects, small world and so on. 2) Obesity in children and adolescents is interpersonal dissemination or infection, which shows a distinct cluster of people. 3) The social network features of young people, such as centrality, homophily, interactivity and diffusivity, affects the interpersonal transmission and contagion of obesity,which are important dynamic factors of interpersonal spread in obesity. The conclusion is that, in view of the accelerating social diffusion of obesity inchildren and adolescents, it is half the work with double results to conduct physical activity intervention based on social network.

Key words: children and adolescents, obesity, social network, homophily, peer effects.