Abstract: Objective:To get Yunnan Lemongrass essential oil by stage extraction,the paper investigates the antioxidant activity on edible fats. Methods :With steam distillation stage extraction to obtain the essential oil.With the lard and rapeseed oil as the medium,and the Peroxide Value as the index,the antioxidant activities of the tracts and its collaborative antioxidant effect with VCwere investigated. The various antioxidant activities were compared with the BHT and BHA. Results:The technology conditions for extracting the essential oil from the lemon grass by steam distillation were as follows:the material-liquid ratio of 1 ∶20,Distillation time of 160 min and the mass concentration of Na Cl was 7g/L,the total oil yield was 1.23%. The extraction process of volatile oils was divided into two stages considering the color change of the oils. The distillation time was first20 min and 20~160min. The contents of the main components of the oils were obviously different in two fractions.The 20 ~160min fractions had good antioxidant activity to rapeseed oil and had same antioxidant activity with BHT when used with VC. But antioxidant activity of lemongrass essential oil in lard was low. The DPPH·scavenging ability of 20~160min fractions was worse than BHT and BHA,but had same total antioxidant activity with them. Conclusion:Lemongrass oil had good antioxidant activity,and compounds of high boiling point demonstrated more antioxidant activity than low ones.