公司债券在金融市场中承担着资源重组和融资等重要角色。我国的债券行业自上世纪80年代改革开放之后逐渐兴起，在近十几年间发展尤为迅速，但与之相随的便是债券违约情况的出现。2012年，我国多只公司债爆发信用违约危机，风暴过后人们冷静下来思考，认为信用风险是我国债券市场发展必然要经历的阶段，因而我们应该加强对信用风险的识别和管理，对发行主体和债券做出风险衡量与信用评级，从而稳定债券市场。

我国信用评级行业起步较晚，目前我国关于信用评级的文献重点探索单一评级与债券利差的关系，而关于多重信用评级的研究较少。本文重点研究公司债券发行人多重信用评级对债券利差的影响机制，根据国内外文献结合我国国情提出若干假说进行实证分析并给出政策建议，为提升我国评级行业市场公信力和国际竞争力以及为投资者做出科学投资决策提供有效建议和理论支撑。

本文选用2010年至2020年间发行的一般公司债数据，采用实证检验探索公司债券发行人多重信用评级对债券利差的作用机制。本文研究结果表明：（1）借款人在发行债券前申请不同评级机构进行主体评级的数量越多，其所发行债券的利差越小；（2）当发行人申请的多重评级结果一致时，融资成本较小；（3）发行人历史信用评级趋势为上升或者稳定不变时，其所发行债券利差较小。以上结论与借款人信誉相关的信息不对称的减小以及监管成本的降低有关。

基于以上结论，参考我国信用评级市场的真实状况，本文总结出有针对性的政策建议：（1）规范化信用评级机构进行评级业务时参照的统一标准，标准化评级程序和业务规则；（2）建立统一规范的对于主体和债项的信用评级监管体系，严格执行评级市场的准入和退出机制；（3）推广投资者付费模式，规避评级购买行为的发生。这对我国证监委进一步完善信贷市场监管制度和券商评级披露制度提供理论支撑和政策建议有着重要意义。

Issuing bonds is one of the most important channels for companies to conduct financing activities. Corporate bonds plays an important role in financing and capital allocation in the capital market. China's bond industry has gradually risen since the reform and opening up in the 1980s, and has developed particularly rapidly in the past decade or so. But at the same time, the bond defaults emerged. In 2012, a number of corporate bonds in China defaulted. After that people calmed down and thought that credit risk is a stage that must be experienced in the development of China's bond market. Therefore, we should strengthen the identification and management of credit risk, perform risk assessments on bonds and issuers to stabilize the bond market.

China's credit rating industry started relatively late. At present, China's research on credit ratings mainly focuses on exploring the relationship between single ratings and bond spreads, while there is less research on multiple credit ratings. This article focuses on the mechanism of bond issuers' multiple credit ratings on bond spreads. Based on domestic and foreign literature and in combination with China ’s national conditions, we put forward several hypotheses to conduct empirical analysis and provide policy recommendations. Help China’s rating industry to enhance market credibility and international competitiveness, and help investors to make scientific investment decisions.

This article uses general corporate bond data issued between 2010 and 2020 to study the effect of bond issuers' multiple credit ratings on bond spreads through empirical analysis. The results of this study show that: (1) the greater the number of credit rating agencies that borrowers applying for ratings before issuing bonds, the smaller the bond spreads are; (2) When the multiple rating results applied by the issuer are consistent, financing costs are small; (3) When the issuer ’s historical credit rating trend is up or stable, the bond spreads are small. These results are related to the reduction of the asymmetry of information and supervision costs.

Based on the above conclusions and in combination with the actual situation of China's credit rating market, we also put forward corresponding policy recommendations: (1) Improving the laws and regulations of the credit rating industry and regulating the rating guidelines of credit rating agencies; (2) Establishing a unified and standardized credit supervision system of issuers and bonds; (3) Further implement the "investor payment" model of bond ratings to avoid the occurrence of rating purchases. This is of great significance for the China Securities Regulatory Commission to further improve the rating disclosure system of securities firms and provide theoretical support and policy recommendations.