As a new business operation mode of offline experience and online purchase, showrooming is developing rapidly in the field of Omni channel retail. The promotion effect of offline retailer services on manufacturers’ demands for online direct marketing channels may inhibit retailers’ enthusiasm to provide services and aggravate the conflicts between channels. To solve this problem, a dual-channel supply chain system is composed of a manufacturer and a retailer is studied. The centralized scenario without and with showrooming and the decentralized scenario with showrooming are constructed. The influence of showrooming on optimal pricing, service level, demand, and profit is analyzed, and a service cost-sharing contract is put forward. It is found that the enhancement of the showrooming effect will not reduce the service level and retail price, but it will increase the profits of supply chain members, and the service cost-sharing contract can make the supply chain achieve perfect coordination. Finally, the effectiveness of the coordination strategy is verified by numerical experiments.