The core/shell SiO2 encapsulated with polyacrylamide (SiOx/PAM) nanospheres were successfully prepared by the radical copolymerization of acrylamide (AM) and a macromonomer, methacryloxypropyl SiOx (MP-SiOx) nanoparticles, initiated with AIBN via a facile precipitation polymerization method in ethanol. The percentage of encapsulating (PE%) and the conversion of the AM (C%) of 327.5% and 93%, respectively, were achieved after a polymerizing time of 3 h. The formation mechanism of the core/shell SiOx/PAM nanospheres was explained. The nanospheres were characterized by elemental analysis (EA), Fourier transform infrared ( FTIR), X-ray photoelectron spectrometer (XPS) and transmission electron microscope (TEM).