Abstract: To establish a low-carbon industrial system，promote firms green transformation，advocate green low-carbon consumption and control greenhouse gas emissions，the National Development and Reform Commission launched lowcarbon city pilot policy in 2010 and further expanded the scope of the pilot in 2012 and 2017 Firms not only explicitly integrate green development strategies into their core business，but also set higher green and environmental standards for the upstream firms，driving the transition of supply chains towards more sustainable development To explore whether the downstream demand for lowcarbon and environmental protection can be transmitted along the supply chain to the upstream firms after environmental regulation，which in turn affects the green lowcarbon technology innovation of upstream firms，this paper utilizes the sample of the listed firms major customers and green lowcarbon technology to empirically examine supply chain spillovers of environmental regulations basad on the lowcarbon city pilot policy The results are as follows：
The green low-carbon technology innovation of firms will be significantly improved after the city where the major customers are located is affected by the policy Regarding the economic degree，the affected firms green lowcarbon technology patents will increase by 0225，which accounts for 27506% of the sample average green lowcarbon technology patents The mechanism analysis shows that customer environmental regulation promotes firms green lowcarbon technology innovations by inducing them to increase relationshipspecific investments and improve knowledge sharing in the supply chain The spillover effect is more prominent in hightech industries，firms with higher market position and product uniqueness，and firms with stronger customer bargaining power In addition，the supply chain spillovers of customer environmental regulations can enhance green investors attention and improve operational efficiency as well as large customer stability
The main innovations of this paper include：First，it broadens the research scope of the implementation effect of low-carbon city pilot policy Second，it innovatively reveals the spillover effect of environmental regulation in supply chain networks，and deepens the understanding of supply chain externalities Third，it provides a new way to effectively promote firms green lowcarbon technology innovation This study helps to comprehensively understand the policy effect of environmental regulation and provide a powerful reference for promoting firms green innovation

Key words: environmental regulations, low-carbon city pilot policy, supply chain spillover, green low-carbon technology innovation

摘要： 本文以低碳城市试点政策为准自然实验，实证检验了客户环境规制的供应链溢出效应。研究发现，大客户所在城市受到试点政策影响后，企业的绿色低碳技术创新会显著提高。其影响机制是，客户环境规制可以增加企业的关系专用性投资并提高供应链知识共享水平。这一溢出效应在高科技行业、市场地位与产品独特性较高及客户议价能力较强的企业中更为明显。此外，客户环境规制带来的供应链溢出效应会提升企业的绿色投资者关注度、提高企业的运营效率与大客户稳定性。本文有助于更全面地理解环境规制的政策效应，为推动企业绿色创新提供了参考。

关键词: 环境规制, 低碳城市试点, 供应链溢出, 绿色低碳技术创新