担保等增信措施对国内债券发行定价的影响与国外市场表现不一致的情况已得到学者讨论，而对资产证券化领域相关现象的关注较少。自2014年后，我国资产证券化产品发行由审批制转为备案制，资产证券化业务蓬勃发展，对资产支持证券开展研究的重要性已经大有提升。本文分析外部增信措施对资产支持证券的发行利差的影响，首先对前人关于资产支持证券定价、增信措施对发行利差的影响等领域的文献进行梳理和总结，并介绍了目前国内资产证券化业务的发展历程和市场情况，最后进行实证分析，分析得出结论和政策建议。实证研究方面，本文手动整理了2012年至2023年5月期间，我国发行的全部资产证券化产品相关数据，以发行利差作为被解释变量，以有无外部增信措施为解释变量进行实证研究，证明了采取外部增信措施的资产支持证券，发行利差更高；进一步分析了项目质量分布、投资者可获得信息量、发行主体信用风险会影响上述作用的发挥。本文同时对发行主体采取外部增信措施的动机进行了研究，发现资信情况越差的发行人越可能采取外部增信措施。最后，本文对导致上述结果的可能原因进行了分析，发现“评级包装”机制可能适用于资产支持证券的发行定价过程，并导致了采取外部增信措施反而提升发行利差这一现象。此外，本文使用替换被解释变量、替换解释变量、替换控制变量、改变选取样本时间区间、增大样本缩尾比例、工具变量法等方法进行稳健性检验，检验得出采取外部增信措施的资产支持证券，发行利差更高的结论具有稳健性。本文丰富了资产证券化定价领域的相关研究，并提示资产证券化产品投资者提高对于发行主体采取外部增信措施动机和评级有效性的关注。

The inconsistency between the impact of credit enhancement measures such as guarantees on the pricing of domestic bond issuance and the performance of foreign markets has been discussed by scholars, while less attention has been paid to related phenomena in the field of asset securitization. Since 2014, domestic asset-backed security issuance has changed from an approval system to a filing system, and thus asset-backed security market has flourished. In this case, the importance of research on asset-backed securities has greatly increased.This paper analyzes the impact of external credit enhancement measures on the interest rate spread of asset-backed securities. It reviews and summarizes the existing literatures on the pricing of asset-backed securities, introduces the development process and market conditions of the asset securitization, conducts an empirical analysis and finally draws conclusions and policy recommendations.In terms of empirical research, this paper manually sorts out the relevant data of all domestic asset-back securities during the period from 2012 to May 2023, conducting empirical research with the interest rate spread as the explained variable and the external credit enhancement measures as the explanatory variable. This paper proves that asset-backed securities that adopt external credit enhancement measures have higher issue interest rate spread. Further analysis proves that the perceived project quality distribution, the amount of information available to investors, and the credit risk of the issuer will affect the above-mentioned effects. Meanwhile, this paper studies the motivation of issuers to adopt external credit enhancement measures, and finds that issuers with worse credit status are more likely to adopt external credit enhancement measures. Finally, this paper analyzes the possible reasons leading to the above results, and finds that the "rating dressing" mechanism may be applicable to the issue pricing process of asset-backed securities, which leads to the phenomenon that the adoption of external credit enhancement measures increases the issue interest rate spread.In addition, this paper uses methods such as replacing the explained variable, replacing the explanatory variable, replacing the control variable, changing the selected sample time interval, increasing the sample shrinkage ratio, instrumental variable method to conduct robustness tests. And the results confirm that asset-backed securities that adopt external credit enhancement measures have a higher issue interest rate spread is robust. This paper enriches the relevant research in the field of asset securitization pricing, and reminds investors of asset-backed securities to pay more attention to the motivation of issuers to adopt external credit enhancement measures and the effectiveness of ratings.