债务融资是企业融资的重要手段之一，债务融资能否顺利进行对市场资源配置效率有重要的影响。因此，企业债务融资成本的影响因素是学界和业界重点关注的领域。而股权集中度作为公司治理结构的重要指标之一，一直是热门研究话题。根据国内外已有的研究，股权集中度对于企业的治理水平以及融资决策有着重要的影响，因此，探究股权集中度与企业债务融资成本之间的关系对于指导债务融资的顺利进行具有重要的现实意义。目前已有一些研究针对二者间的关系进行了探讨，但对于二者间的关系的影响因素研究还不是非常充分，因此，本文希望通过理论分析和实证分析，在探讨二者间关系的基础上，重点分析其影响因素。在理论分析层面，公司中同时存在投资人与管理层之间的代理问题，和股东与债权人之间的代理问题。对于前者，股权集中度越高，股东越能对管理层工作进行有效监督，从而提升公司业绩并降低债务融资成本；对于后者，股权集中度越高，股东越可能侵占债权人利益，从而升高债务融资成本。在实证分析层面，本文利用CSMAR数据库中的2003-2018年我国A股上市公司数据进行分析发现，股权集中度越高，企业债务融资成本越低，这说明在现实中，股东对于管理层监督的作用强于股东侵占债权人利益的作用，从而导致前一种所带来的债务融资成本降低的效应成为主要影响。本文进一步分析了股权制衡度、股权性质、杠杆率、两权分离率、公司规模五大影响因素，通过实证分析的方式探究其对于前文结论的影响。回归结果显示，对于股权制衡度高、有国企背景、杠杆率低、两权分离率高、公司规模小的企业，股权集中度与企业债务融资成本之间的负相关关系将更为显著。本文的研究结论提示企业应当完善自身治理结构，加强股东对管理层的控制力度，从而降低管理层的代理风险问题，这样能够降低债务融资成本。而债权人面对融资企业，应当重点考察其治理结构中的股权集中度、股权制衡度、股权性质、杠杆率、两权分离率、公司规模等因素，从而进行合理的定价。本文丰富了关于股权集中度与企业债务融资成本的相关研究，并且着重研究了二者间关系的影响因素，对现有研究进行了一定的有益补充。

Debt financing is an important part of corporate financing. Whether debt financing can be carried out smoothly has an important impact on the efficiency of market resource allocation. Therefore, the influencing factors of the cost of corporate debt financing have attracted great attention of academy and industry. On the other hand, ownership concentration degree is an important indicator of corporate governance structure and also has been a hot research topic. According to existing research, ownership concentration has an important impact on corporate governance and financing decision. Therefore, exploring the relationship between ownership concentration and corporate debt financing costs is of great practical significance for both the financing companies and the creditors, facilitating the debt financing. There are already some studies focusing on the relationship between the two factors, but not enough studies focusing on the influencing factors on the relationship. Therefore, this paper will focus on the influencing factors on the basis of the discussion of the relationship through theoretical analysis and empirical analysis.In the aspect of theoretical analysis, there are two types of agency problems. One is between the company managers and the investors, including shareholders and creditors, while the other is between shareholders and creditors. For the former, the higher the ownership concentration degree, the more effectively shareholders can supervise the daily work of the management, thereby reducing the cost of debt financing. On the other hand, for the latter, the higher the ownership concentration degree, the more likely shareholders are to encroach on the interests of creditors, thereby increasing the cost of debt financing.In the aspect of empirical analysis, this paper uses the data of China's A-share listed companies from 2003 to 2018 from the CSMAR database to explore the relationship between ownership concentration and corporate debt financing costs. Through empirical analysis, it is found that the higher the concentration of equity, the lower the cost of corporate debt financing, which proves that in reality, the effect of shareholders’ role in management supervision is stronger than that of shareholders’ encroachment on creditors’ interests. Therefore, the effect of reducing financing costs has become the main effect.In order to further study the relationship, this paper analyzes five major influencing factors, namely ownership restriction, nature of equity, leverage ratio, separation of control and ownership, and size of the companies, and conducts further empirical analysis to explore the impact of the five major influencing factors on the previous conclusions. The regression results show that for companies with a high degree of equity restriction, state-owned equities, low leverage ratio, high separation of control and ownership, and a small company size, the negative correlation between ownership concentration and corporate debt financing costs will be more significant.The research conclusions in this paper suggest that companies should improve their own governance structure and strengthen shareholders’ control over management, thereby reducing management’s agency risk, which can reduce debt financing costs. And for creditors, it is of great importance to conduct thorough investigation on financing companies and pay attention to main influencing factors such as ownership concentration degrees, ownership restriction, nature of equity, leverage ratio, separation of control and ownership, and company size, so as to make reasonable pricing. The paper enriches the research on ownership concentration and corporate debt financing cost. What’s more, it supplements the research of the influencing factors of the relationship between the two.