ATRP-template dispersion polymerization of methacrylic acid(MAA) on the template of polyvinyl pyrrolidone(PVP K-30) was carried out in the aqueous solution by using methyl 2-bromopropionate(MBP)/CuCl/2,2?-bipyridine(bpy) as the initiation system. The scanning electron microscopy(SEM), dynamic light scattering(DLS) and gel permeation chromatography(GPC) were employed for evaluating the results of polymerization. As a result, the minimonomer droplets formed due to the H-bond interaction of PVP-MAA. The stability of droplets was dependent on pH and the concentrations of both PVP and MAA. When pH < 2, the coagulum of PVP-MAA formed, whereas when pH > 4.5, the droplets were not observable by DLS. In order to prepare the stable latex, the concentration of PVP should be lower than 9 wt%, whilst the concentration of MAA should be lower than 5.5 wt%. The optimum condition was pH 2.4, PVP 4.76 wt% and MAA 5 wt%, by which the stable latex of ca. 50 nm nanoparticles of PMAA/PVP was prepared by ATRP polymerization and simultaneously the molar mass of PVP was duplicated by PMAA according to GPC diagrams. In contrast, by using AIBN, KPS and KPS-Na2SO3 redox initiation system, the coagulum accompanying with the larger molar mass of PMAA was obtained, irrespective of pH and concentrations of PVP and MAA. ATRP-template dispersion polymerization of methacrylic acid (MAA) on the template of polyvinyl pyrrolidone (PVP K-30) was carried out in aqueous solution by using methyl 2-bromopropionate (MBP) / CuCl / 2,2- As a result of the initiation system. The scanning electron microscopy (SEM), dynamic light scattering (DLS) and gel permeation chromatography (GPC) were employed for evaluating the results of polymerization. As a result, the minimonomer droplets formed due to the H-bond When pH <2, the coagulum of PVP-MAA formed, while when pH> 4.5, the droplets were not observed by DLS. The order of concentration of PVP should be lower than 9 wt%, while the concentration of MAA should be lower than 5.5 wt%. The optimum condition was pH 2.4, PVP 4.76 wt% and MAA 5 wt% by which the stable latex of ca. 50 nm nanoparticles of PMAA / PVP was prepared by ATR Pration and simultaneously the molar mass of PVP was duplicated by PMAA according to GPC diagrams. In contrast, by using AIBN, KPS and KPS-Na2SO3 redox initiation system, the coagulum accompanying with the larger molar mass of PMAA was obtained, irrespective of pH and concentrations of PVP and MAA.