开发区政策对推动我国城市高质量发展具有不可或缺的重要作用，但开发区建设过程所存在的产城分离问题是否随着发展得到改善，产城融合程度是否影响其对城市创新作用尚不明确。基于此，本文将经济技术开发区由省级升格为国家级作为准自然实验，从产城融合视角验证了开发区升格对城市创新水平的作用机制。研究表明：开发区升格能有效促进其所在城市创新产出提高，且通过一系列稳健性检验；产城融合是开发区升格所在城市创新增长的重要原因，其主要通过促进服务共享、要素畅通和协同创新等对城市创新起到正向影响。进一步地，受地理区位、发展水平影响，开发区升格带来的城市创新数量和创新质量促进效应有所差异；开发区升格政策还具有线性“叠加效应”，随着升格次数的增加对城市创新的推动作用增强。

In the process of China""s reform and opening up, the policy of development zones has played an indispensable and important role in promoting China""s economic development and technological progress, and its role in promoting city innovation has been unanimously recognized by the academic community. However, it is unclear whether the problem of industry-city separation existing in the construction process of development zones has been improved with development, and whether the degree of industry-city integration affects the role of development zones on urban innovation. Based on this question, this paper uses a quasi-natural experiment of upgrading economic and technological development zones from provincial to national level during the period 2009-2019, and verifies the mechanism of the effect of upgrading development zones on urban innovation from the perspective of city-industry integration using a double difference method. The study shows that the upgrading of development zones can effectively promote the quantity and quality of innovation in the cities in which they are located, and passes a series of robustness tests; the city-industry integration is an important reason for the increase in the quantity and quality of innovation in the cities in which the zones are upgraded, mainly through the promotion of service sharing, factor flow and collaborative innovation. Further, depending on the geographical location and development level, the quantitative and qualitative effects of upgrading of development zones vary, with positive effects on the innovation level of cities in central, western and northeastern regions, except in the east, and a significant incentive effect on innovation-following cities. The policy of upgrading development zones also has a linear "superposition effect", with the number of upgrades increasing to boost the level of urban innovation.

F20

国家自然科学基金面上项目“中国对外直接投资企业的创新绩效研究:基于ESCP分析框架”(72273051)、国家自然科学基金面上项目“中国对外直接投资企业选址、进入策略与经营绩效提升研究:基于多维制度距离和多元化组织学习视角”(71773040)。