Abstract: Aiming at the large-scale 3D city modeling and collaborative database applications,a high-performance 3D GIS database engine is designed and developed,which supports the multimode database management based on Oracle 11g DBMS.This paper presents a new 3D spatial database model concerned with semantics for the integrative management of outdoor & indoor and aboveground & underground 3D spatial data,then introduces related key technologies such as hierarchical 3D spatial index,multilevel caches,multithread dispatch and asynchronous communication and transmission.By means of the real 3D city models of Wuhan city,the experimental results prove the validity of this engine.