Abstract: Huge risk exists in web service because of many cheatings and malicious acts in the open environment of internet with web services. So it’s a trend to build an effective trust mechanism based on web services. According to the characteristic of web service, a new trust evaluation model is proposed. In this trust model for web services reduces to trust degree of business and trust degree of customer evaluation. During implementing trust degree evaluation, it is necessary to think about the influence of service time, service result and malicious behavior to trust degree as pivot, and it designs a new web services architecture grounded on the new trust evaluation model, and explains the application of web services under the new architecture also. Simulation experimental results show the new trust evaluation model can distinguish the cheating and malicious act in web services.