Ordering and pricing are the most critical aspects of an e-commerce retailer's operations. Retailers' pricing decisions affect the demand of potential consumers in the marketplace, while appropriate order quantity decisions can help companies optimize their supply chain and logistics management, thereby improving their profitability. Based on the pre-sale background in the e-commerce industry, this paper considers consumer strategic behaviour and the product diffusion effect. Moreover, the theory related to expected utility and differential equation is used to design and solve a two-stage sales model of retailer expected revenue gives the optimal pre-sale pricing and order quantity considering linear diffusion effect and convex product diffusion effect. This paper guides e-commerce retailers to make pre-sale pricing and ordering strategies and has implications for them.