Abstract: P(Am-co-VAc) sizes were synthesized through emulsion and dispersion polymerizations respectively.The influences of the two polymerization methods on the viscosity,adhesion-to-fiber,and film behaviors of the sizes were investigated by the comparative analysis.The result demonstrates that P(Am-co-VAc) sizes prepared through emulsion polymerization are advantageous over those through dispersion polymerizations in adhesion-to-fiber,break strength and breaking elongation of the film and water solubility but similar moisture absorption property.The emulsion polymerization is beneficial to raising the application behavior of the sizing agents.