The invention relates to a phosphorothioate type antiwear agent, and in particular relates to a compound of formula I, wherein R1 and R2 are independently selected from C1-12 straight or branched chain alkyl groups, R3 and R4 are each independently selected from the group consisting of H, C1-12 straight or branched chain alkyl groups, C1-12 straight or branched chain alkyloxy groups, and the C1-12 straight or branched chain alkyl groups and the C1-12 straight or branched chain alkyloxy groups are optionally mono-substituted or polysubstituted by substitutes selected from the group consisting of a halogen, C1-4 alkyl groups, halogen-substituted C1-4 alkyl groups, C1-4 alkoxy groups, halogen-substituted C1-4 alkoxy groups, hydroxyl groups, cyano groups, nitro groups, amino groups or trifluoromethyl groups. The compound as a hydraulic oil or lubricating oil additive exhibits excellent rust resistance, good antiwear property, thermal stability, filtration and hydrolytic stability.