This study was laid out in Lorestan agricultural farm, Korramabad, Iran during 2016 and 2017. The experiment was designed based on a complete randomized design (CRD) with four replications. In this study, in the spring, fresh leaf samples were randomly collected seven species of Eucalyptus. The composition of essential oils determined using analytical gas chromatography coupled to mass spectrometry (GC-MS). The results showed that the effect of specie treatment was significant on essential oil yield, alpha-Pinene, beta-Pinene, 1, 8-Cineole, gamma-Terpinene, Pinocarvone, Epiglobulol and beta-Eudesmol. Based on our results, essential oil of Eucalyptus camaldulensis Dehnh. was obtained at rate of 3.43%. The measured oil yield was in range of 2.57% for Eucalyptus nitens (H. Deane & Maiden) Maiden, 1.34% for Eucalyptus globulosusbicosata, 5% for E. globulus madidenii17746, 5.38% for E. globulusmadidenii 2130, 3.74% for Eucalyptus viminalisLabill.and 1.12% for Eucalyptus suggrandis L.A.S. Johnson & K.D. Hill. The main compounds of Eucalyptus camaldulensis Dehnh. oils were 1, 8-cineole (66.72%) followed by alpha-pinned (17.88) in the samples. The major constituents of Eucalyptus nitens (H. Deane & Maiden) Maidenoils were 1, 8-cineole (46.67%), alpha-pinene (14.56%) and beta-Pinene (4.51%). The main components of E. globulus oils were 1, 8-cineole (70.15%) and alpha-pinene (3.65%). The main compounds of E.globulusmadidenii17746 oils were 1,8-cineole (55.82%), alpha-pinene (3.91%) and Veridiflorol (5.07%). The major constituents of E. globulusmadidenii 12130 were 1,8-cineole (60.29%), alpha-pinene (15.5%), alpha-Terpineol (6.11%) and Eudesmol (3.88%). The major constituents of Eucalyptus viminalis Labill. oils were 1, 8-cineole (56.43%), alpha-pinene (3.91%). The major constituents of Eucalyptus suggrandis L.A.S. Johnson & K.D. Hill oils were 1, 8-cineole (30.94%), alpha-pinene (18.52%), beta-Eudesmol (6.87%) and Pinocarvone (4.96%). The E. globules maidenii 12130 specie had highest rate of essential oil yield. Between all species E. suggrandis had maximum rate of alpha-Pinene, gamma-terpinene, Pinocarvone and beta-Eudesmol. Between essential oil compositions 1, 8-Cineole was in higher rate especially in E. globules bicostata specie.