The jurisprudential connotation of the “ensuring the basics” principle in basic medical insurance is to safeguard people’s “economic security” in the diagnosis and treatment of illness. This principle is grounded in the legal system of basic medical insurance benefits, which defines the scope of insured events, medical services and cost-sharing, and is dynamically adjusted in line with socioeconomic development, so as to clarify the specific limits of people’s right to claim basic medical insurance benefits. Based on the jurisprudential connotation of “ensuring the basics” and its legal logic, under the objective of “ensuring basic survival”, the policy scope of “prioritizing major illnesses while also covering minor illnesses” established in China’s current policy documents on basic medical insurance within the limit of “moderate medical security” still shows a certain deviation from this principle. With the Medical Security Law on the legislative agenda, it is necessary to reconstruct and optimize the benefit norms of basic medical insurance through legal integration, legal reservation, and rule-of-law decision-making, so as to promote the maturity and regularization of the basic medical insurance legal system.