Abstract: The flow and circulation of low-carbon technology knowledge is an inherent requirement for building a new pattern of "dual circulation" and promoting sustainable economic growth under the "dual carbon" goal, but there is a lack of domestic policy research. Based on the balance panel data of 218 prefecture-level cities in China from 2006 to 2019, this paper reflects the overall flow of low-carbon technology knowledge with patent information, and uses the multi-point DID method to empirically test the impact and mechanism of low-carbon city pilot policies on low-carbon technology knowledge flow. The results show that: (1) The low-carbon city pilot policy can effectively promote the flow of low-carbon technology knowledge in general, but it is mainly manifested in accelerating the inflow of low-carbon technology knowledge. However, it has not shown the effect of the pilot policy on the spillover of low-carbon technology knowledge. This may be related to the insufficient demonstration effect of pilot policies. (2) Pilot policies can promote the knowledge flow of gray and clean technologies, but they have a more significant effect on gray technologies with more gradual and incremental characteristics, which is contrary to the reality that clean technology knowledge flows very quickly. (3) A higher level of human capital and industrial structure in pilot cities will help strengthen the promotion role of low-carbon city pilot policies, and the policy effects will be more obvious in the eastern and central regions, first- and second-tier and non-resource-based cities. Therefore, we should actively promote the demonstration and expansion of low-carbon city pilots, activate clean technology activities, and try to adopt differentiated pilot policies; The eastern and central regions and major cities should give full play to their existing talent and industry advantages, actively support the development of clean technology, and lead the deep low-carbon transformation; The western region, small and medium-sized cities, and resource-based cities should pay more attention to the coordination of pilot policies with other policies, so as to form a policy synergy to promote knowledge flow.

摘要： 低碳技术知识的流动与循环是“双碳”目标下构建“双循环”开放新格局、促进可持续经济增长的内在要求，但国内驱动政策研究缺乏。本文基于2006-2019年中国218个地级市的平衡面板数据，以专利信息反映低碳技术知识流动，采用多时点DID方法实证检验国内低碳城市试点政策对低碳技术知识流动的影响及作用机理。研究发现：（1）低碳城市试点政策能够在总体上有效促进低碳技术知识流动，但主要表现为加快低碳技术知识流入，而试点政策对低碳技术知识溢出的促进作用没有显现。表明试点的示范效应不足。（2）试点政策能够促进灰色与清洁两类技术的知识流动，但对更具渐进增量特点的灰色技术作用更加显著，这与清洁技术知识流动速度极快的现实形成较大反差。（3）试点城市更高水平的人力资本与产业结构层次有助于强化低碳城市试点政策的促进作用，且东中部地区、一、二线和非资源型城市的政策效果更加明显。因此，应积极推动低碳城市试点的示范推广与扩区工作，激活清洁技术活动，并尝试采用差异化的试点政策；东中部地区与大城市应利用人才与产业等优势扶持清洁技术，引领深度低碳转型；西部地区、中小规模、资源型城市更应注重试点与其他政策的协同，以形成促进知识流动的政策合力。