To realize cloud manufacturing (CMfg) production in group enterprises, manufacturing resources and modeling technologies of cloud pool were studied. According to the characteristics of group enterprises, manufacturing resources were analyzed and classified into human, equipment, materials, cooperation resources and so on. Then, the realization method which manufacturing resources mapped into virtual resources was researched, and a layer platform for cloud manufacturing was proposed. Taking CNC machine tool as an example, the ontology model was built with Semantic Web and OWL based on ontology theory. Finally, using semantic similarity computation method and case-based reasoning, the virtual resources were intelligent searched and matched so that manufacturing resources can realize unification, sharing and reuse.