This study examines the effects of influencing parameters to Eucalyptus globulus essential oil (EOs) in the hydrodistillation process including extraction temperature, time, and raw material to water ratio. The study also investigated the chemical composition of Eucalyptus globulus EOs by Gas chromatography-Mass Spectrometry (GC-MS). Based on the single factor investigation method, the yield of the EOs for 2.2% in the conditions including the leaves size about 0.5 mm, with the ratio of the leaves to water was 1:4 (g/mL), at 75 minutes in the extracting temperature of 120°C. The analytical results showed that the composition of Eucalyptol (35,034%), followed by α-Pinene (17,860%), β-Pinene (11,022%), α-Terpenol (4,756%), caryophyllene oxide (4,554%), camphol (2,123%), and other ingredients with content less than 1%.