(3,4-Diphenyl-2,5-dimethyl)phenyl-poly(vinyl silicon) oils (DPDMP-C-gums) have been synthesized by Diels-Alder reaction of polyvinyl silicon oil (C-gum) with 3,4-diphenyl-2,5-dimethylcyclopentadienone (DDCP) in diphenyl ether at reflux temperature under normal pressure. The structures of the prepared compounds were characterized by H-1-NMR, IR, and UV spectra, and some of their properties, such as color, viscosity, refractive index, and thermooxidative stability of the DPDMP-C-gums, were obtained.