This paper first establishes the index system of high-quality economic development and realizes the calculation of economic high-quality development score with the help of the entropy value method and coupling mechanism. Secondly, by constructing a spatial autocorrelation model, the spatial spillover effect of new infrastructure on high-quality economic development is empirically investigated. The mediation effect of digital new infrastructure on economic high-quality development through industrial structure and technological progress is continued to be analyzed. Finally, based on the panel data of 30 Chinese provinces from 2008 to 2020, the dynamic panel threshold model and the dynamic spatial Durbin model are used to test the nonlinear effects of financial resource allocation on the convergence of high-quality economic development and the mechanism of action, respectively. It is found that the direct effect coefficient of digital new infrastructure is 0.002 with a p-value less than 5%, and the indirect effect coefficient is 0.004, which passes the significance test at the 1% level. It is conducive to promoting high-quality economic development, and the allocation of financial resources can significantly enhance the role of new digital infrastructure in promoting high-quality economic development. Accordingly, implementing the new digital infrastructure proposed in this paper has contributed to the modernization of government governance, optimized the allocation of financial resources, and promoted high-quality economic development.