In this paper, a scheme of message signature and encryption based on Simple Object Access Protocol (SOAP) is designed for the intelligent decision-making system of real estate to solve communication security issues when interacting data with other heterogeneous systems. Referring to the national recommendations upon the information security area in the e-government implementing process and considering both efficiency and security of communication procedures between two endpoints, we screened and integrated various security methods, then implemented a security platform with C# and WSE3.0. The experiment shows its good safety, reliability, flexibility, manageability, and scalability.