This paper focuses on the key algorithms and techniques for developing an interactive visual retrieval system for large scale 3D databases, and a novel 3D model retrieval and visualization engine, 3DMIRACLES, has been developed, which integrates effective algorithms and techniques for both shape-based retrieval of 3D models and real-time visualization of the retrieval results in realistic 3D interactive mode. In the retrieval system, interactive visualization for the retrieval user interface and 3D shape retrieval computation are the two most important functional modules. For interactive visualization, a novel 3D viewer has been developed, which implements hybrid rendering method to make much simplification and shortcut processing of 3D rendering computation for achieving high speed and efficient visualization of large scale database; for retrieval computation, new algorithms for 3D shape feature extraction and similarity matching have been developed and implemented.