The servitization of manufacturing has led enterprises to extend their core businesses to service industry. With the constraints of operational cost and service capacity, service is provided by either a supplier or a third-party service provider to achieve a higher service level for customers, thereby forming the vertical channel and networked channel respectively. This paper models and optimizes both channels. By comparing the service level, market supply and the profits of supply chain members, the optimal channel structures in different scenarios are discussed. The results show that the channel structure has no impact on service level if the service cost is constant. The optimal channel structure is determined by the service costs of suppliers and third-party service providers: if the service cost of the third-party service provider is low enough, service outsourcing and networked channel should be adopted to achieve Pareto Improvement.