Abstract: In the critical period of solidly promoting common prosperity, fully leveraging policy advantages is of great significance for urban-rural common prosperity, but few scholars have focused on the impact of the county-level basic financial guarantee mechanism policy on urban-rural common prosperity. Based on panel data from 572 county-level districts from 2011 to 2022, the county-level basic financial guarantee mechanism is regarded as a quasi natural experiment to innovatively empirically test the impact and path of the construction of the basic financial security mechanism at the county level on the common prosperity of urban and rural areas.Research has found that the construction of county-level basic financial security mechanisms has a positive promoting effect on the common prosperity of urban and rural areas, and this conclusion still holds after a series of robustness tests. Heterogeneity testing found that compared to the eastern, central, and northeastern regions, as well as county-level areas with higher levels of labor factor transfer, the construction of county-level basic financial security mechanisms has a more significant promoting effect on the common prosperity of urban and rural areas in the western region and county-level areas with lower levels of labor factor transfer. The inspection of the intermediary mechanism found that the construction of the basic financial security mechanism at the county level mainly indirectly promotes the common prosperity of urban and rural areas by adjusting the distortion of capital allocation and balancing the supply of public services. The regulatory effect test confirms that digital inclusive finance plays a regulatory role in promoting common prosperity between urban and rural areas through the construction of county-level basic financial security mechanisms. The research conclusion provides new experience for the development of urban and rural common prosperity from the policy perspective of building a county-level basic financial guarantee mechanism, and also provides new reference for better playing the promoting role of county-level basic financial guarantee mechanism construction in promoting common prosperity from the perspectives of regulating capital allocation distortion, balancing public service supply, and digital inclusive finance.

Key words: in the critical period of solidly promoting common prosperity, fullya county-level basic financial guarantee mechanism, common prosperity between urban and rural areas, public service supply, allocation of capital, digital inclusive finance