Achillea millefolium belong to the asteraceae family and from genus achillea. In this study essential oils were extracted from all aerial parts via hydro distillation (HD) method by clevenger set . By using of gas chromatography/mass spectrometry ( GC-MS) technique the chemicals component essential oil were identified. About 41 components with were identified which encompassed 97.66 percent of the whole essential oil. The essential oil yields as a result of hydro distillation 0.56 percent (weight/weight) was obtained (it has been based on dried materials). In essential oils Achillea millefolium dihydrocarveol (34.97%), umbelulone (16.65%), 1,8 cineole (14.94%), bornyl acetate (6.08%), chrysanthenyle acetate cis (5.24%), camphene (4.21%), para-cymene (3.29%) and α-pinene (3.24%) were the major identified compounds. The purpose of this study was to identify the constituents of essential oils extracted from plants and also to determine the percentage of each compound in the essential oil of Achillea millefolium used as drug.