With the rapid development of the new media era, the influence of media on children becomes more and more obvious in the process of socialization. Growing up in this context, left-behind children have also become one of the main groups using social media, with the characteristics of high frequency of use and different preferences. Through reviewing previous research, this paper aims to understand the use of social media in daily life of left-behind children, analyze its impact on the socialization of left-behind children, explore the underlying reasons, and summarize the relationship between the use of social media and media literacy of left-behind children. When left-behind children have high media literacy, they do not have excessive dependence and tend to browse beneficial social media content; while when their media literacy is low, they will have a high sense of dependence on media and contact with bad social media content. Socialization process of left-behind children in China is subject to many restrictions and challenges. Social media is an important way for left-behind children to communicate with the outside world, obtain information and establish social relationships. Therefore, studying the impact of social media on the socialization of left-behind children can help future research explore how to better use social media to promote the socialization process of left-behind children, and provide a basis for formulating relevant policies and measures. Future studies should cover different regions and combine quantitative and qualitative methods to better understand the process of socialization of left-behind children.