Abstract: EGCG water in oil( W/ O) antioxidant microemulsion( ME) was prepared by use of isopropyl myristate as oil phase,tween 80 and span 80( HLB 6) as surfactant,ethanol as cosurfactant( Km 4 ∶ 1),and its stability and antioxidant activity were studied. The type of ME was identified by measuring the electrical conductivity,and the stability of ME was evaluated through measuring the size of ME and the impact of storage time on the ME size under 25 ℃ condition. The antioxidant activity of ME was measured by Rancimat oxidative stability analyzer in peanut oil and flaxseed oil.The results showed that the appearance of the ME was clear and transparent,the ME size changed little and exhibited good stability when stored at 25 ℃ for 50 d,meanwhile,the ME had strong antioxidant activity in vegetable oil.