Most of the current research work on web service selection only considered the selection problem from the perspective of one party – service consumers. A service marketplace serves many parties including service consumers and providers. Thus, it is important to consider multiple parties. In this thesis, we propose a service selection model considering the benefits of multiple parties: consumers, providers and the marketplace. The model ranks services based on not only how much these services satisfy the user requirements but also how much the requests can be distributed to different providers and the revenue gain in the marketplace. We design different objective functions, then combine into a QoS-Plus-PF objective function. The results show that proposed model could achieve a high degree of satisfaction of user requests (i.e., 0.61% to 5.26% worse than the optimal score), and meanwhile have the capability of promoting more diversified set of services (i.e., 48.95% promotion percentage).