随着行业集中化趋势和头部企业在供应链中的主导地位强化，供应链管理实践中大客户“兼任”供应商的现象日益普遍，但随着“紫晶存储”事件爆发，大客户“兼任”供应商能否赋能企业高质量发展成为学术界讨论焦点。本文选取2007—2022年A股上市公司为研究对象，运用面板固定效应模型与准自然实验相结合的方法，研究大客户“兼任”供应商对节点企业创新效率的影响，并发现：第一，大客户“兼任”供应商对企业创新效率具有负向影响；第二，其中的作用机制表现为增大企业融资约束和降低供应链效率；第三，当企业自身的吸收能力较强、内部控制有效性较高、对供应链依赖度较低、大客户/供应商是国有企业时，大客户“兼任”供应商对企业创新效率的负面影响能够得到有效缓解。本文将供应商与客户纳入统一研究框架，基于更加完整的视角关注了供应链关系对企业创新的影响，丰富了既有文献，同时为管理实践中加强对大客户“兼任”供应商行为的监管，抑制其中的机会主义行为，赋能企业高质量发展提供了参考。

With the trend towards industry concentration and strengthening of the dominant position of top enterprises in the supply chain，the phenomenon of key customer-supplier duality in the supply chain management practice is becoming increasingly common. However，with the outbreak of the "Amethystum" incident，whether key customer-supplier duality can empower enterprises to develop with high quality has become a focus of academic discussion. This paper selected A-share listed companies from 2007 to 2022 as the research object，and used a combination of panel fixed effects model and quasi-natural experiments to study the impact of key customer-supplier duality on the innovation efficiency of node enterprises. It was found that： firstly，key customer-supplier duality has a negative impact on the innovation efficiency of enterprises；secondly，the mechanism is manifested as increasing corporate financing constraints and reducing supply chain efficiency；thirdly，when a company has strong absorption capacity，effective internal control，low dependence on the supply chain，and its key customers/suppliers are state-owned enterprises，the negative impact of key customer-supplier duality on the corporate innovation efficiency can be effectively alleviated. This paper has incorporated suppliers and customers into a unified research framework，focusing on the impact of supply chain relationships on enterprise innovation from a more comprehensive perspective and enriched existing literature，and it will provide reference for strengthening the supervision of key customer-supplier duality behavior in management practice，suppressing opportunistic behavior，and empowering high-quality development of enterprises.