A series of styrene/acrylate modified waterborne alkyd resin with different ratio of styrene and acrylate were synthesized via a two-step process. The structure, component and molecular weight of the modified alkyd resins were characterized by FT-IR, ~1H-NMR and GPC. A varnish was prepared by diluting the said resin with water and its film performance was determined in terms of drying time, pencil hardness, adhesion, resistance to water and alkaline. The results showed that the styrene/acrylate (molar ratio 1 : 1. 6) modified waterborne alkyd resin exhibited excellent physical properties.