This paper constructs the game models of supply chain under the dual-channel and O2O modes, and studies the pricing and mode selection in a supply chain under the influence of showrooming effect. The results show that: no matter what the channel mode is, offline showroom service and showrooming effect make the manufacturer and retailer increase the retail prices of both online and offline channels. The manufacturer decreases the wholesale price under dual-channel mode, while it does not necessarily reduce the wholesale price under O2O mode. The offline showroom service and showrooming effect increase the demand of online and offline channels. As the retailer’s profit is increased, who would like to provide offline showroom service and accept O2O mode. The manufacturer will also choose O2O mode, when the showrooming effect is negligible, which can improve the operation efficiency of supply chain under most conditions. Therefore, when the showrooming effect and the proportion of online channel demand meet certain conditions, O2O mode is the consistent choice of the manufacturer and retailer, which realizes the successful transformation from dual-channel mode to O2O mode.