Abstract: With the standard development of the e-commerce and consumer credit business, many e-commerce platforms have launched consumer credit service. While at the same time, the phenomenon of high returns is particularly prominent. Considering the endogeneity strategy of e-commerce platforms to launch or not launch consumer credit service, the paper conducts a stylized model, which shows the interaction between product return and consumer credit service strategy by establishing the product return utility decision-making model affected by the coefficient of pain buffering. Then this paper analyses how product return rate and coefficient of pain buffering influence on optimal product pricing, demand, and corporate profits. The research found that: 1) Considering product return, it is not always beneficial for e-commerce platform to launch consumer credit service. When the expected return value loss rate is low, it is beneficial for the platform to launch consumer credit service. When the expected return value loss rate is high, it is harmful for the platform to launch consumer credit service; 2) When launching consumer credit service, demand could probably drop. Although the pain buffering effect of consumer credit service could increase consumer purchase intention, its disutility also reduces their purchase intention. At this time, manufacturers also seek opportunities to increase product prices, which may ultimately reduce consumer purchase intention, and this leads to a decrease in product demand; 3) When the expected return value loss rate is low enough, only when the e-commerce platform launches consumer credit services can it achieve a "triple win" for the interests of the platform, manufacturer and bank. This article explores the interactive impact of consumer credit services and consumer returns on e-commerce platforms, promoting interdisciplinary research in the fields of platform economy and consumer behavior, platform consumer finance, and consumer returns,; The research results of this article provide new ideas for the governance of e-commerce platforms, especially providing theoretical guidance that is more in line with user psychological behavior and return practices for platform consumer credit service decision-making.

Key words: E-commerce platform, consumer credit service, product returns, coefficient of pain buffering, Game theory