This work is part of the chemical composition’s study, of the essential oil’s and antifungal activity. This oil is extracted, from an aromatic and medicinal plant of the Algerian flora, in order to find new metabolite products, which are characterized by a biological activity. The investigations and research on the essential oil; extracted from the dried aerial part of Artemisia Herba alba, which was harvested in the region of Djelfa (South of Algeria); and separated by gas chromatography coupled by a mass spectrometry (GC/MS); resulted in obtaining Thirty-three constituents, representing 97.54% of the essential oil of Artemisia Herba alba. The main compounds identified are Davanone (42.8%), Camphor (15.96%) and Thujone (9.63%). The antifungal activity of oils was tested using the direct contact method against the growth of Fusarium moniliforme, Fusarium solani, Fusarium oxysporum and Stemphyliumsolani. Our results clearly demonstrate that the essential oil could supply a valid alternative to chemical treatments on the basis of their efficacy on different types of plant pathogens and their flexibility of use.