Abstract: Through participatory observation, in-depth interviews and thematic analysis, this study explores the self-presentation and construction process of men's masculinity within the context of fitness culture in China. The research finds that, in the fitness process, the self-presentation of men's masculinity is primarily manifested in such aspects as personal qualities and appearance, physical capabilities, handling of gender relations, and the hierarchy within fitness culture. Furthermore, the self-construction of men's masculinity encompasses a process of 3 stages, including the self-discipline, self-adjustment and resistance, followed by a re-examination and multifaceted understanding. The study points out that the self-presentation and masculinity construction are realized through an embodied process of individual experiences and social interactions, with fitness providing a crucial space for men to seek personalized self-expression and identity recognition within the norms of social culture. Through fitness activities, Chinese men not only display traditional masculine traits of strength and health but also showcase a diversity of personalization and inner qualities, which will lead them to find a more equal and inclusive relocation in social gender roles. This research offers a new perspective for understanding gender relations in China and helps in alleviating the anxiety men face between traditional and modern roles, promoting the acceptance and understanding of diverse masculinities.