With China's historic eradication of absolute poverty, the promotion of common prosperity has become an inevitable requirement for building a modern socialist country in an all-round way. The medical insurance, assistance system for major, serious diseases has played an active role in reducing the burden of medical expenses for the poor, the seriously ill, preventing their return to poverty caused by illness. With the implementation of universal medical insurance, the scope of assistance has been expanded, the level of assistance, security has been improved, however, there are still some outstanding difficulties in the system to meet the basic medical, health needs of the people in need, better achieving "medical care for the sick". In October2021, the "Opinions on Improving the Medical Insurance, Assistance System for Major Diseases" was issued, which made overall arrangements for the medical insurance, assistance system for major diseases in the future, will further consolidate the underlying guarantee mechanism of the universal medical security system, improve the long-term mechanism to prevent, alleviate poverty, returning to poverty due to illness. This paper discusses the development process of institutional construction, analyzes content of the latest institutional reform, explores the future development