Costco is one of the four leading retailers in the world, offering customers a wide range of products at low prices and with high quality. As a low-cost leader, Costco still achieved amazing growth despite the impact of the epidemic. The purpose of this paper is to explore the business model and financial analysis of retailer Costco. This paper adopts the method of case study to discuss Costco's existing business model, strategic and competitive advantages and financial indicators. Provides Costco with a detailed analysis of its business activities relative to industry competitors in order to generate profits and maximize shareholder value. Data is collected from multiple secondary sources to ensure the authenticity of the information. In terms of business model, Costco is significantly affected by the macro environment, mainly due to COVID-19. Secondly, with the rapid economic development, online shopping is becoming more and more popular among young people, so the competition is becoming more and more fierce. Costco shows a flexible business model in its financial analysis. This article provides help for corporate managers, other retailers in the industry and researchers.