(Silver-poly(4-vinylpyridine))(Ag-P4VP) hybrid microgels were synthesized by γ-irradiation and surfactant-free emulsion polymerization in a single step.The effects of dose rate and the concentrations of isopropanol,silver ion,N,N′-methylenebisacrylamide(Bis) and 4-vinylpyridine(4-VP) on the hybrid microgels were studied in detail via transmission electron microscopy(TEM),powder X-ray diffraction(XRD) or dynamic light scattering(DLS).The results indicated that the size of Ag nanoparticles in the hybrid microgels increased with the increase of Ag^+ or Bis concentration and with the decrease of dose rate or isopropanol concentration.When the dose rate was decreased,the phase state of Ag nanoparticles was gradually transformed from amorphous state to cubic crystalline state.Although the variety of the P4VP microgels’ size was more complex,it could also be easily adjusted by the above-mentioned conditions.