In this paper we present a new mapping approach of owl ontologies, using the reuse technics. We propose also a refinement technic of mapping, to make it more pertinent. Our Mapping approach focuses on computing semantic similarity between concepts of ontologies to map, it is based on a weighted combination of computing similarity methods, we use syntactic, lexical, structural, and semantic technics. The proposed mapping and refinement process makes use of several types of information in a manner that increases the mapping accuracy.