In this paper, the problems exposed by the third generation of supervisory control and data acquisition (SCADA) based on the portable operating system interface of UNIX (POSIX) standards for UNIX systems are analyzed. Then, a new power SCADA based on the four-tier architecture of J2EE platform is built. The common information model (CIM) database and graphics elements of scalable vector graphics (SVG) are created on the basis of CIM models of International Electrotechnical Commission (IEC) 61970. This design approach makes the system produce device models and topology automatically while generating SVG graphics and thus implements integrative graphic model library. Because of poor information sharing and interoperability of common object request broker architecture (CORBA) as the integration bus among power systems, the component interface specification (CIS) interfaces are implemented by Web services, which result in the seamless integration between SCADA and other systems and such integration is standard and open. The combination of enterprise JavaBeans (EJB) and Hibernate to implement the business logic and make data be persistent separately also makes the SCADA much more scalable and flexible. Because of its flexibility and extensibility, this new SCADA has great benefit to the automation course of electric power systems.