Rosin-styrene acrylic composite emulsion was prepared by emulsion polymerization using styrene(St), methyl methacrylate(MMA), 2- ethylhexyl acrylate(2-EHA), 2-hydroxyethyl acrylate and acrylic acid as monomer. Using rosin emulsion as modifier made rosin styrene acrylic composite emulsion by emulsion polymerization. The effects of the amount of emulsifier, initiator, rosin emulsion and the ratio of monomer on the properties of emulsion were discussed. Then the composite emulsion was characterized by thermogravimetric analysis (TGA), dynamic light scattering particle size analysis (DLS), transmission electron microscopy (TEM). The results showed that the resulting emulsion with its particle size of 127 nm presented white with blue phase when the amount of the emulsifier, initiator ,rosin emulsion , hard and soft monomer ratio were 5wt%, 0.8wt% , 30wt% and 2.5:1,respectively. And more, the resulting film was absolutely smooth and transparent with good hardness, water resistance and adhesion properties.