Abstract: This paper discusses an engineering database management system——EDBMS/3.Based on extending and modifying EDBMS/2 which is designed and implemented by CAD Laboratory of the institute of Computing Technology. Academia Sinica,EDBMS/3 supplies stronger capacity of Data Definition Language (DDL) and Data Manipulation Language (DML).The effective management for a resident data area, a transient area and a free area in main memory reduces the table swapping between the main memory and the disk. The paper defines R-type tuple network structure to prevent possible system error and data inconsistency. The management and manipulation for multimedia data means the system has the ability of processing dynamic multimedia data such as a period of sounds and a section of images.