Abstract:This paper studied the essential oil collected at different distillation periods from Cymbopogon citratus（DC）Stapf.The essential oil was extracted by steam distillation and analyzed by gas chromatography-mass spectrometry（GC-MS）. The antioxidant ability of essential oil were evaluated by DPPH radical scavenging method and ABTS+ radical cation scavenging method. It was found that 32，35，34 and 34 components of essential oil were identified in 0-10，10-30，30-60 min and 60-360 min distillation stages respectively. The main components and their relative content were different in each distillation stage. 0-10，10-30，30-60 min distillation periods were rich in neral（35.33%，31.58%，28.47%）and geranial（38.50%，32.99%，37.56%）.The major components in 60～360 min distillation periods were n-hexadecanoic acid（18.24%），neral（8.49%）and geranial（12.05%）. The IC50 values of essential oil for scavenging DPPH radical were 16.05，7.89，4.03 mg/mL and 1.47 mg/mL，respectively，during different distillation periods. The IC50 values for ABTS+ radical scavenging were 3.58，2.40，1.08 mg/mL and 0.55 mg/mL，respectively. In conclusion，the essential oil of Cymbopogon citratus（DC）Stapf possessed strong antioxidant activities，and the essential oil collected at 60～360 min showed the strongest scavenging activities on DPPH and ABTS+free radicals.