Abstract: Ontology mapping created by end-users contains class hierarchy structure knowledge of the domain，and using that knowledge can produce new domainal ontology mapping.Current system considers the complexity of class hierarchy and applies “equals to” relationship.But in the inference process，current system deletes inconsistent knowledge arbitrarily which would impact the recall.Aiming at solving those problems，this paper proposes a new concept of reliability of source.Besides，this paper re-designs inferences on class hierarchy knowledge base.The experiment result shows that revised system is more precise than the original one in knowledge structure，and can produce results with higher recall while maintaining high precision.