Objective: The paper clarifies the connotation and implementation of the basic guarantee function of the medical assistance system under the goal of common prosperity, identifies constraining factors, and proposes countermeasures and suggestions. Methods: We conduct literature review and descriptive analysis of relevant public data concerning the core issues. Results: In recent years, the overall expenditure and number of beneficiaries of the urban and rural medical assistance system is increasing significantly. The per capita assistance for subsidized individuals is increasing year by year, while the average assistance for direct assistance is gradually decreasing. Compared with the per capita premium and hospitalization expenses, the proportion of per capita assistance for subsidized insured patients to the per capita premium for basic medical insurance dropped. Conclusion: The medical assistance system is subordinate to the ultimate goal of common prosperity. If the medical assistance system is designed properly and can be operated efficiently, it can provide strong support for the goal of common prosperity. However, compared to the growing demand for assistance, the funding investment of the medical assistance system is to some extent insufficient in recent years, resulting in a decrease in the actual level of assistance. The basic guarantee function still needs to be strengthened. We need to forge a common understanding, clarify security objectives, optimize assistance policies, improve financing mechanisms, strengthen supply and demand management, and further improve the medical assistance system.