To achieve the goal of manufacturing automation, the knowledge integration in collaborative process is very crucial, especially, the heterogeneous information distributed among various cooperative suppliers. Therefore, an ontology-based methodology of knowledge integration is proposed to solve the information heterogeneity in this study. By representing a collaborative business activities for cooperative suppliers, a framework of knowledge integration with ontological schema is generated. Aiming for the schema, an approach of ontology integration on the basis of ontological similarity is promoted. There are two portions included in this approach, mapping and combination, which are implemented through the analysis in similarity of universal and regional two ontologies. To integrate the two ontologies, the relations and restrictions among fields are definitely depicted by semantic web rule language. Eventually, the proposed framework is demonstrated by CNC-WEDM process, and the outcomes satisfy the needs of the knowledge integration to assure that validity of the proposed approach is confirmed.