The medical‒prevention integration drives the development of the health service system, reorients health services toward health itself, and links prevention, screening, diagnosis and treatment, rehabilitation, and health management into a continuous service chain. Therefore, building a public health system characterized by medical‒prevention integration and health co-governance has become a major national imperative. This study conceptualizes the public health system as a complex socio-technical system and follows a systems engineering methodology of "problem definition‒case learning‒challenge identification‒architecture design‒implementation pathway" to explore the theoretical logic and technical architecture of medical‒prevention integration in promoting the development of a health co-governance-oriented public health system. After clarifying the research approach and defining basic concepts, the study analyzes four types of medical‒prevention integration practices: medical and prevention coordination in infectious disease prevention and control in China, international comprehensive prevention and control of infectious diseases, integration of chronic disease prevention and treatment in China, and international chronic disease management. Moreover, it summarizes three typical models: emergency collaboration in China, incentive-based international chronic disease management, and primary-level integration in China. It also identifies current development challenges facing medical‒prevention integration, including institutional barriers in the organizational system, deviations in economic incentive orientation, structural shortages of interdisciplinary professionals, fragmentation of information systems, and institutional obstacles to social participation. Accordingly, the study constructs a "four-layer, three-interface" technical architecture for a medical‒prevention integration system, encompassing data, platform, application, and governance layers as well as information, incentive, and capacity interfaces. This architecture integrates data standardization, operational collaboration, scenario-based service delivery, and governance institutionalization into a unified framework, providing a systematic response to deep-seated problems such as information silos, incentive misalignment, and capacity gaps. It is advisable to establish unified data governance and exchange standards, develop a shared business platform for medical and prevention coordination, build a competency-oriented talent cultivation system, design an incentive-compatible institutional framework, construct a platform for multi-stakeholder participation, and adopt a progressive implementation strategy, so as to precisely advance the development of the medical‒prevention integration system and support the high-quality development of the healthcare sector.