Abstract: High-quality economic development is an inevitable requirement for achieving Chinese type modernization, and digital infrastructure is an important support for realizing economic transformation and upgrading. Based on the panel data of 41 cities in the Yangtze River Delta from 2010 to 2022, this article explores the impact of digital infrastructure on the high-quality economic development and its spatial spillover effects, and conducts a convergence analysis on it. The research results show that digital infrastructure has significantly promoted the high-quality economic development of the Yangtze River Delta region. The promoting effect of digital governance on digital infrastructure shows a significant positive moderating effect, and the research conclusion remains valid after the robustness test. The heterogeneity analysis reveals that under different urban scales, the promoting effect of digital infrastructure on the economic vitality of non-large cities is significantly higher than that on other cities. The analysis of spatial spillover effects indicates that digital infrastructure not only significantly promotes the economic growth of local cities but also demonstrates a strong radiation effect on the economic growth of surrounding cities. The spatial convergence analysis indicates that β convergence exists in large cities, while α and β convergence occur simultaneously in non-large cities. This suggests that the moderating effect of digital infrastructure on the convergence speed of high-quality economic development in non-large cities is more significant than that in large cities. The above results indicate that strengthening the construction of digital infrastructure by the government has important policy significance in promoting regional coordinated development.

Key words: digital infrastructure, digital governance, high-quality economic development, spatial spillover effect, convergence analysis