For resolving problems such as how the user implement three-dimensional CAD model retrievals and how to reuse the retrieval results during the smart process planning, this paper present an ontology-based algorithm for three-dimensional CAD model retrieval. The CAD model is segmented into several relevant sub-parts. Then, attach semantic descriptions and annotations to these sub-parts. Finally, evaluate the similarity of the models based on the semantic ontology 3D CAD model. The experimental results show the efficiency of this method to meet the requirements of engineering retrieval and reuse of design and manufacture.