Abstract: General Secretary Xi Jinping has proposed that "people's health should be given top priority in development" and that "the focus of medical treatment should be changed to the focus of people's health" in implementing the Healthy China Strategy. Based on the law of disease spectrum evolution, this paper explains the evolution and development process of the medical security system with prevention and treatment as the center since the founding of the People's Republic of China. From the 1950s to the 1970s, China actively carried out the patriotic health campaign, established a medical security system with prevention as the center, and effectively prevented and treated malignant infectious diseases. From the 1980s to the 1990s, China gradually realized a basic medical security system that covers all people, with treatment as the center, creating a safety net for all members of the society against disease risks. In the 21st century, with the change of disease spectrum and the aging of the population, chronic diseases have become a major health threat to the elderly population in China. On the basis of analyzing the internal factors of heredity, education, occupation, age and family that affect the health of the aged population and the group environmental factors such as economy, service and environment that affect the health of the aged population, it is pointed out that "prevention" is the meaning of "health" and "health" is the rational choice of "cure". "Health centeredness" is a new era medical security concept that includes "health, prevention, treatment and rehabilitation". This paper puts forward the construction path of health-centered medical security system for the elderly in China, that is, constructing economic support system and social service support system to meet the medical and health needs of the elderly, and creating an age-friendly social environment.