There are a wide range of defects in the market role in the medical and health field. Among them, public health is regarded as a very typical example. There are pure public goods with externalities in the field of public health, such as safe provision of drinking water, prevention of infectious diseases and parasites, control of pathogenic vectors and other free services. Because these goods are obviously non-exclusive, that is, people without wealth are not excluded from enjoying the benefits of this service, therefore, private individuals will not provide them at all or cannot provide them completely. Provide a premise for fair income distribution. The market distributes income according to the individual's capital contribution to labor, and the contribution of labor is based on personal health. Under the market rules, it is difficult for low-income people to resist poor health conditions and disease risks, and they often fall into a strange circle of diseases. Government intervention is to regard medical care as everyone's right, ensure everyone's healthy work, and reduce or eliminate the possible adverse effects on health due to income gap. Make up for the defects of commercial insurance. The risk of disease is the most unpredictable. In the private market, people buy commercial insurance, but the profit-seeking nature of commercial insurance will inevitably lead to adverse selection, that is, choosing low-risk insurance objects. The government's public health service has the nature of social insurance, so that the risk of diseases will be borne by the government in a larger scope, and high-risk groups will not be excluded. In this way, it can provide a strong backing for workers. Scope of government intervention: public health services: various health services provided to meet the public's public health needs and achieve a healthy and safe public environment, mainly including planned immunization, infectious disease control, maternal and child health care, drinking water safety, environmental sanitation, health education, etc. Basic medical services: basic medical services that provide all people with the necessary medicines and diagnosis and treatment methods for most common and frequently-occurring diseases and meet the basic health needs of all citizens.