Consumer finance has penetrated into people’s daily life, especially in the field of e-commerce online shopping. In order to stimulate consumers’ desire to buy, adjusting credit line has become the marketing strategy of many merchants. However, little research has been done on whether this method can really cause consumers to buy impulsively. This paper discusses the relationship between the credit line adjustment of e-commerce consumer finance and the impulse purchasing desire of consumers in the context of online sales promotion in the “double eleven shopping festival”. In this research, data is collected by adopting simulated methods, and the data is analyzed through the SPSS. The research result shows that the increase of the consumption finance credit line positively affects the consumer impulse purchasing desire, and positive emotion has mediating effect; the results of this research can help e-commerce platforms to manage the credit line reasonably and formulate effective marketing strategies to enhance its competitiveness in the online market.