The functional characteristics and the nonfunctional properties of service profile always play very important roles in composite semantic web service selection approach. But the credibility of this information cannot be guaranteed. This paper established a novel trust degree model of this information. Based on this model, the trust degrees can be calculated from execution log and user experience evaluation of candidate web services. Then the paper proposes a new composite semantic web service selection approach based on this credible information. Finally, we present two experiments to prove that the new approach can avoid the influence of exaggerated and unauthentic information effectively and accurately.