Internetware is built upon the coordination of the heterogeneous, autonomous software entities in the open coordination environment. But it is very difficult to select the honest coordination software entities with dependable quality of services to build the trusted Internetware because of the openness and dynamic of the Internet. Trust relationships among software entities will provide important information about the selections of trusted coordination entities. The trust relationships are always changing along with the co-operations of software entities. However, the existing trust models cannot support the automatic formation and update of the trust relationships among entities, and cannot reflect the dynamic attribute of the trust relationships. This paper presents a trust measurement and evolution model for the Internetware. The model abstracts the process of the trust measurement, transfer and combination rationally and provides a reasonable approach to form and update trust relationships automatically. This model is helpful to solve the problem of the trustworthiness of the Internetware.