In this study, the essential oil content in the aerial parts of Cleome heratensis which is growing in the east of Iran was investigated. The aerial parts of the plant were collected from the late August to October 2014, for a total of four harvests (S1-S4). Essential oils were isolated by hydro-distillation. The oils were analyzed by GC-FID and 30 constituents, representing 84.93-92.9 % of the total compositions of the oil were identified. The major components of the essential oil in the four harvests were hexanal (7.57%-33.96%), α-phellandrene (6.08% -13.17%), α-farnesen (7.54%-10.9%), methyl eugenol (6.74%-8.31%), eugenol (3.94%-7.4%), verbenone (3.98%-6.24%), myrcene (1.54%-5.75%), hexadecane (2.34%-4.82%), linalool (1.59% - 3.53%) and α-humulene (1.01%-1.93%). The findings indicated That the main component groups of oil are monoterpenoids (11.83–19.29%), oxygenated monoterpens (10.34–16.96%), sesquiterpenoids (10.67–20%) and oxygenated sesquiterpenes (0–4.34%) which are obviously increased during the growing stages. Monoterpenoids were higher during the late flowering stage (S3), but oxygenated monoterpens were observed to be slightly lower in this stage. Monoterpens are slightly higher during development stages.