This paper presents the design and implementation of one object-oriented EMS real-time database. The database is constructed by the dynamic modeling technology based on the meta-data and meta-rules, conforms to IEC61970 standard. Compare to the relational and hierarchical database, the object-oriented database has the better openness and interoperability. The dynamic modeling technology based on the meta-data and meta-rules is that in which the object models are created completely on the most basic data medium- meta-data and the most basic method which describe relations -meta-rules. The technology can construct various application objects in the different fields. Based on this dynamic modeling technology, the models are constructed by dynamic-modeling tool. The data models can be created and modified without programming by this tool. That improves the stability of system greatly. In the process of design and develop of the EMS database, the hierarchical characteristic of power system and the characteristic of dynamic modeling technology are all be considered to design the objects and attributes what raise the queries and access speed. The real time database uses the parallel databases cloning technology which solves the problem of data coupling between multi-applications. Based on the cloning technology, the polymorphism database is provided which can meet the requirement of multi-study and multi-application. Through testing, the database can fill the requirements of the real power system.