The medical assistance system can help reduce the burden of medical expenses for seriously ill patients, maintain people's health, improve people's lives and promote common prosperity. This paper analyzes the effect of medical assistance expenditure in Shanxi Province from 2006 to 2019 through the vector autoregression model, explores the shortcomings of the medical assistance system in Shanxi Province under the background of common prosperity, and puts forward suggestions for improvement. It has important research significance for consolidating and expanding the achievements of poverty alleviation to effectively connect rural revitalization and promoting common prosperity.