This work is inspired by the intend to construct SOABased E-Government. We first emphasize the importance of taking measures for solving security problems facing Web Services, we then have an in-depth look at SOA-Based Web Services, including its architecture, underlying technologies, transmission model, and SOAP message. By leveraging the understanding of securing Web Services, we conclude that the essentials of achieving trustworthy SOA-Based Web Services are to accomplish the task of attestation and authorization of ultimate service endpoints, and to establish trustworthy service channel between them. Furthermore, the XML-Based cryptographic techniques and contemporary strategy for achieving trustworthy SOA-Based Web Services are introduced. Specifically, WS-Security is detailed in terms of accomplishing essential tasks of achieving trustworthy SOA-Based Web Services.