The aim of this reserch was determining of the Achillea wilhelmsii C. Koch essential oils composiation that was growned in natural counditions.Collected plants were harvested at full bloom stage in july 2019 and dried in the shade of the room condition then pulverized in the form of a homogeneous mixture and its essential oil was extracted by distillation with water. The components of the essential oil were identified and measured using the gas chromatography device connected to the mass spectrometer. The results showed that the essential oil obtained from the dried vegetative body of the plant had a yellow color with a yield of 0.89%. The results of GC-MS showed that the essential oil of this plant in the desired area consisted of a combination of 106 substances. Percentage of total essential oil, the most important main compounds identified in essential oil were: α-Thujene (2.21%) Camphene (2.38%), Sabinene (0.53%), Eucalyptol(1,8-cineole) (5.71%), Terpinen-4-ol (2/55%), Nonanal (4/25%), Camphor (9/87%), (+) 2 Bornanone (5/59%), Endo-borneol (4/05%), α-Terpineo (2/46%), Rosefuran (3/52%) Caryophyllene (0.64%), α-Farnesen (1.83), Terpinolene (3.44%) and Caryophyllene oxide (5.62) -Based on our knowledge this is the first report of Zanjan Achillea wilhelmsii C. Koch.