Based on China's provincial panel data from 2007 to 2020, the entropy method, coupling coordination model and spatial econometric model were used to explore the coupling coordination level and influencing factors of social assistance common prosperity. The research results show that at the overall level, social assistance has promoted the overall development level of common prosperity, and the number students in higher education and the elderly population support ratio have a positive spatial spillover effect on the coupling coordination degree of social assistance and common prosperity. At the level, the coupling coordination of the three regions is specifically manifested as the central region>the eastern region>the western region, with regional differences.