The healthcare security system serves as a crucial component of the national governance framework and constitutes a foundational institutional arrangement for advancing the Healthy China strategy and the goal of common prosperity. This study systematically reviews the evolution of China's healthcare security enrollment model, tracing its development from "automatic inclusion" to the current phase of precision governance, and attempts to construct a theoretical framework for this distinctively Chinese approach. Empirical analysis based on national enrollment data from 2024 indicates that China's medical insurance efforts, building upon a foundation of high coverage rates, are progressing toward higher quality and greater sustainability. While challenges persist in further expanding enrollment, the focus must be on optimizing the enrollment structure, refining financing mechanisms, enhancing data sharing, improving grassroots service delivery, and ensuring that the institutional design better accommodates new developmental realities such as population mobility and emerging forms of employment. Drawing upon insights from local governance innovations and examining experience from Southeast Asian and BRICS countries regarding "legislative mandates, fiscal support, and data-driven approaches", and in consideration of the requirements for medical insurance enrollment within the context of Chinese modernization and common prosperity, this paper proposes several reform recommendations. These include establishing a family-based enrollment system, exploring a potential transition from insurance premiums to a tax-based model, creating automatic enrollment mechanisms tailored for the platform economy, and implementing exemption policies for the very young and the elderly.