As a popular innovation, Web Service provides a flexible solution to integrate diverse online applications with existing Internet protocols and open standards. The availability and flexibility of Web Service enable its potential to handle dynamic requests in distributed online collaboration.However, this potential is limited by Web Service’s security concerns due to its uncertainty, openness and fraudulence. A solution to this problem, Trust, an important social concept in all human interactions, has been proven to be a promising way to resolve the security issues raised by these distributed collaborations.This paper introduces a novel evaluation model of Web Service by leveraging trust as an approach. We first incorporate a trust management module into the standard Service Oriented Architecture (SOA). Then, after transforming a Web Service network to a small-world network based on the trust relationships of service entities, we propose a trust evaluation model with an amendatory subjective logic. The simulation experiments we ran compared our trust evaluation model with two other popular models. The result shows our proposed model outperforms in terms of both detection capability and stability.