Abstract: As a representative form of contemporary youth subculture, fandom culture not only reflects young people's creative expression, strong organizational capacity, and emotional community building, but also reveals their lived experiences and value dilemmas. In the era of artificial intelligence, algorithms have become a new governing logic of social operation. While empowering youth cultural practices, they also profoundly reshape the internal logic and external forms of fandom culture, generating a series of challenges. At the level of content production, algorithmic recommendation mechanisms contribute to thematic homogenization and the formation of information cocoons; at the level of community structure, algorithm-driven interaction patterns foster highly cohesive yet exclusionary group formations; and at the level of cognition, algorithmic imaginaries give rise to increased media dependence and data fetishism. The evolving ecosystem of fandom culture further influences adolescents' perceptions of the world, problem-solving patterns, and value formation, leading to multiple dilemmas, including cognitive narrowing and weakened critical thinking, polarized group identity and confrontational behavior, as well as the quantification and instrumentalization of values. To address these challenges, it is necessary to adopt a three-dimensional approach: dismantling information cocoons, overcoming community boundaries, and transcending algorithmic constraints. Such efforts can guide adolescents toward cognitive expansion and value reconstruction, providing a reference for the healthy development of adolescent cognition in the digital era.