Abstract: Under the current background of new infrastructure construction, based on the panel data of 283 prefecture level and above cities in China from 2009 to 2017, this paper uses the "gradual" difference in differences model to empirically test the impact of "broadband China" demonstration city construction on innovation capacity. It is found that the construction of "broadband China" demonstration city has significantly improved the city's innovation ability. After parallel trend test, placebo test, PSM-DID method estimation and other robustness tests, the research conclusion is still stable. The results of mechanism test show that the construction of "broadband China" model city can significantly improve the level of urban Internet development, and then drive the improvement of urban innovation capacity. Further research shows that the impact of "broadband China" demonstration city construction on urban innovation capacity is heterogeneous, and the innovation effect is more significant in eastern cities, higher level cities, large-scale cities and cities with higher Internet development level. This study provides a reference for China to further implement the policy of "broadband China" demonstration city construction, improve national independent innovation capacity and accelerate the construction of an innovative country.

摘要： 本文立足于当前新基建的背景，借助中国2009—2017年283个地级及以上城市的面板数据，运用“渐进性”双重差分模型实证检验了“宽带中国”示范城市建设对创新能力的影响。研究发现，“宽带中国”示范城市建设显著提高了城市创新能力，在经过平行趋势检验、安慰剂检验、PSM-DID方法估计以及其他稳健性检验后，研究结论依然稳健。机制检验结果表明，“宽带中国”示范城市建设能显著提高城市互联网发展水平，进而驱动了城市创新能力的提升。进一步研究发现，“宽带中国”示范城市建设对城市创新能力的影响存在异质性，创新效应在东部地区城市、等级较高城市、规模较大城市以及互联网发展水平较高城市更加显著。本文的研究为中国进一步深入实施“宽带中国”示范城市建设政策、提高国家自主创新能力、加快建设创新型国家提供了参考依据。