In 2020, during the peak period of the COVID-19 outbreak in China, the scarcity of medical protective products significantly influenced consumers’ impulsive purchasing and affected the public order. It is important to identify the effect of scarcity on consumers’ impulsive purchasing during this difficult time. However, scant research has been conducted on the impact of scarcity of medical protective products on Chinese consumers’ impulsive purchasing. This paper investigates the impact of the scarcity of medical protective products on consumers’ impulsive purchasing during the pandemic in China based on the theories of scarcity, S-O-R and bandwagon effect. Simultaneously, this study identifies the different mediating mechanisms (fear of missing out and perception) and the moderation (bandwagon) in the relationship between scarcity and impulsive purchasing. Finally, 509 validity data were collected by using an online questionnaire, and SmartPLS was used for data analysis. The findings present that the fear of missing out, perception and bandwagon dominate the scarcity effect on impulsive purchasing. The findings provide more information on consumers’ impulsive purchasing in the context of scarcity of medical protective products. Marketers and the Chinese government can adopt measures to reduce their effect, which may help maintain the public order during the epidemic.