According to the latest advancements of IEC 61970 common information model (CIM), in order to establish perfect power system database and achieve data transformation between different versions of CIM, this paper proposes a solution of electric data storage based on CIM 3.0. The solution adopts Java persistence API (JPA) annotation combined with object-relation mapping (ORM) to design power system database, which is used to solve the current CIM describing data inaccurately in China, the complex process of database development and so on. Through annotations embedded in power system entities to simplify database design, it implements multiple inheritance, association and complex attribute mapping of the power enterprise entity object. Using dom4j to parse standard CIM RDF format electric data, it rebuilds the data and imports database, and finally verifies the integrity of database, which shows the design scheme is feasible and effective.