In order to provide customers with a better shopping experience, many retailers have introduced the buy-online-and-pick-up-in-store (BOPS) shopping channel, so that the limited offline inventory is faced with multiple channels demand. Whether the introduction of BOPS channel is beneficial to retailers and the decision-making optimization of offline limited inventory is still lacking research. This article considers a retailer and two types of customers. One type of customer is physical store customers who purchase goods only through physical stores, and the other type is omnichannel customers who choose among various channels strategically. Existing omnichannel research mostly assumes that retailers’ offline inventory is prioritized to satisfy offline channels. This paper takes three service strategies into consideration, including Store-customer Priority Strategy (SPS），Omnichannel-customer Priority Strategy (OPS) and Equal Priority Strategy (EPS）. Compared with the traditional literature, it is found that the introduction of BOPS is not entirely beneficial to the retailer. The retailer physical store density (determining the customer's store visiting cost) and distribution center density (determining the customer's online waiting cost) will affect the retailer's revenue. At the same time, it is found that if customers' online waiting costs and store visit costs are low, and store visit costs are lower, the introduction of BOPS channels with SPS and EPS, will increase the retailer’s profits, and at the same time increase the consumer surplus of store customers and omnichannel customers.