推进数字治理是中国政府治理改革的重要方向，“国家智慧城市试点工作”是近年来提升城市数字治理能力的重要事件。文章基于东部地区57个城市在第四、五、六次全国县级以上公共图书馆评估定级中的结果数据，采用双重差分法实证检验了智慧城市试点政策作为一种数字治理方式，能否提升公共图书馆的发展水平。研究发现，试点政策有效促进了二级图书馆向一级图书馆升级，但是对于三级图书馆数量影响微弱，反映出政策实施过程中存在的“强者愈强，常者如常”现象。研究丰富和拓展了数字治理政策效果评估的相关内容，为数字治理政策的完善提供了参考。

Advancing digital governance is a key direction in China’s government governance reform, with the “National Smart City Pilot Program” representing an important event to enhance urban digital governance capabilities in recent years. This paper leverages data from the fourth, fifth, and sixth national evaluation and grading of public libraries at or above county level across 57 eastern Chinese cities. Utilizing the difference-in-difference (DID) method, we empirically examine whether the smart city pilot policy, as a form of digital governance, can improve the development level of public libraries. Findings indicate that pilot policies significantly facilitated the upgrading of second-tier libraries to first-tier status, yet exerted minimal effects on third-tier library quantities. This reveals a “the strong get stronger, the ordinary remain ordinary” dynamic in policy implementation. This research contributes to the literature on evaluating digital governance policy effectiveness and provides empirical foundations and policy insights for refining digital governance policies.