Abstract: Waterborne polyurethane(WPU) was modified by epoxidized soybean oil(ESO), methyl methacrylate (MMA), butyl acrylate (BA) and 2-hydroxypropyl acrylate (HPA), to obtain polyurethane-acrylate-ESOhybrid emulsion whichhas a core-shell structure with acrylate as core and polyurethane as shell. The structure and properties of thehybrid emulsion were characterized by Fourier transform infrared (FT-IR) spectra and particle size analyzer. Effects of process parameters on polymerization and dosages of ESO and MMA on properties of thehybrid emulsion and its films were investigated. Results showed that the optimal process was as follows:temperatures of prepolymerization, chain-extending, neutralization and emulsion polymerization were 80,70,40 and 70℃, respectively, times of prepolymerization, chain-extending, emulsion polymerization were 1.5,4-5 and 4-5h,respectively, and rotation rate was 6000r/min.When contents of ESO and MMA were 4%-6% and 30%,respectively,hybrid emulsion with small particle size andgood store stability was prepared. Its filmhadgood media resistance and low water absorption.