Abstract: A liquid sulfur-containing phenol ester antioxidant (KY505) was synthesized by transesterification of methyl 3-(3,5-di-ter-butyl-4-hydroxyphenyl) propionate and 2-(phenylthio ) ethanol. The structure of the product was analyzed by IR and NMR. Then the solubility and anti-oxidation performance of the product was inspected. The results indicate that the antioxidant ability of KY505 is outstanding, and the oil solubility of KY505 is better. The oxidation induction period increases by more than 50%, compared with antioxidants, like hindered phenol type, phenol ester type and thio-phenyl type antioxidant.