It is recognized that knowledge has a considerable usefulness in people's daily life and all businesses. The current paper discusses a knowledge description using ontology and its application in Multi Agent Systems (MAS). The presented work proposes to reach a powerful relationship between MAS and Knowledge Management (KM), principally by introducing results achieved in the semantic web domain to MAS. The proposed method is to apply KM in MAS using ontology, wherever undetermined knowledge is absent. This is an appropriate model for various cases particularly when we require experience management.