With the progress of globalization and the penetration of digital media into people's daily lives, this has brought significant convenience to the dissemination of American TV series in China. At the same time, it has also brought various influences to the Chinese audience, especially for fans of American TV series. These TV series offer rich imaginative resources for their fans. Simultaneously, the internet and social media provide fans with additional channels and spaces to construct new fans identities. It is highly worthwhile to pay attention to how Chinese fans of American TV series creatively utilize these resources on the online platform, and how they construct their identity as fans through practical activities. Therefore, in order to better understand the construction of fan identity, this research focuses on fans of American TV series on the Chinese social media platform Baidu Post Bar. It combines the looking glass self theory and employs virtual ethnography for online participatory observation. The aim is to explore how these fans construct their personal identities through their practices on social platforms. This research found that the construction of individual identities among fans is a complex cultural behavior. They build their identities through a combination of practical activities, personalized text consumption, and the amalgamation of ideal self and peer evaluation. The results of this study also provided a relevant theoretical foundation for understanding the relationship between media usage and audience identification.