Abstract: Lasting buy-it-now auction is a common buy-it-now auction method. Considering the seller selling multiple items, how does the seller formulate the strategy of buy-it-now price and when the bidder chooses the buy-it-now option is a problem that needs to be studied. . Based on the independent private value model, this paper combines the multi-unit Vickrey auction mechanism and the lasting buy-it-now auction to establish a multi-item lasting buy-it-now auction model. By analyzing the expected returns of the bidder and the seller, the bidder's equilibrium bidding strategy and the seller's optimal buy-it-now price are obtained, and through numerical analysis, different strategies are given for both auction bidders and sellers to conduct multi-item lasting buy-it-now auctions online and offline on-site lasting buy-it-now auctions according to the number of items.

Key words: Multi-Item auction, Number of auction items, Buy-it-now auction, Independent private values, Expected benefit