Abstract: In the era of digital intelligence, the quantified self has emerged as a new approach to personal health management and has gained increasing popularity among users. However, limited scholarly attention has been paid to the influencing factors of quantified self behavior from the perspective of the personal information worlds framework. Grounded in digitally intelligent contexts, this study incorporates the concept of "digital identity" to revise and extend the personal information worlds framework, and constructs a four-dimensional influencing factor model encompassing content, boundary, motivation, and digital identity. The fuzzy DEMATEL-based Analytic Network Process (DANP) method is employed to analyze the causal relationships and relative importance of the influencing factors. The results indicate that, based on five indicators—centrality, causality, weight, influence degree, and influenced degree—eight key factors affecting quantified self behavior can be identified across the four dimensions of content, boundary, motivation, and digital identity. Within the digital identity dimension, digital accounts, data privacy, and digital participation are identified as critical factors, forming the foundational conditions for information acquisition and the practice of the quantified self in digital environments. Within the content dimension, four key factors—accessible information sources, obtainable information sources, foundational information sources, and information assets—significantly affect individuals' device engagement and information utilization efficiency. In the boundary dimension, cognitive level determines the quality of data interpretation and decision-making. In the motivation dimension, purposeful information practices drive the sustained optimization of quantified self behaviors.