The dispersion polymerization of VAc initiated by gamma ray irradiation was carried out in polar media using poly (N-vinylpyrrolidone) as a steric stabilizer at room temperature．This method takes advantages of the specialities of radiation induction

and highly uniform polymer microspheres were obtained．The molecular weight of the polymer increased with the increase of stabilizer content and polymerization temperature

and the decrease of absorbed dose rate

monomer concentration

and ratio of alcohol／water. Based on the experimental results (XPS and element analysis)

only the physical adsorption of stabilizer was found in the polymer particles．Compared with other monomers

vinyl acetate may not be inclined to graft-copolymerize with poly(N-vinylpyrrolidone) in radiation polymerization systems．This is maybe due to the low activity of VAc grafting with the stabilizer according to the theory of radiation grafting．