关键词: 数字基础设施, “宽带中国”, 外贸高质量发展

Abstract: As the cornerstone of digital economy development， digital infrastructure plays a critical role in promoting China's economic growth and enhancing the quality of foreign trade. Based on panel data from 263 cities in China from 2010 to 2020， this study treats the “broadband China” demonstration city construction policy as a quasi natural experiment and employs a progressive double difference model to analyze the mechanism and impact effect of digital infrastructure construction on the high quality development of foreign trade. The research finds that the “broadband China” demonstration city construction policy significantly promotes the high quality development of foreign trade， and this promotional effect becomes more evident over time， remaining valid after a series of robustness tests. Heterogeneity analysis results indicate that the promotional effect of digital infrastructure on the high quality development of foreign trade varies by region and city size， with a more significant impact on eastern cities and larger cities. Mechanism testing shows that digital infrastructure promotes the high quality development of foreign trade by enhancing urban technological innovation and deepening marketization. Based on these findings， government departments should actively improve urban digital infrastructure construction， enhance urban innovation levels， and build a unified domestic market to support the high quality development of foreign trade.

Key words: digital infrastructure, “broadband China”, high-quality development of foreign trade