Rosin modified aminopropyltriethoxysilane (RA) was prepared via an epoxide ring opening reaction of rosin based glycidyl ester with aminopropyltriethoxysilane. The structure of RA was confirmed by Fourier transform infrared spectroscopy (FT-IR), 1H NMR, and 13C NMR. RA was used as a cross-linking agent to prepare room temperature vulcanized (RTV) silicone rubber with hydroxy terminated polydimethylsiloxane (PDMS) matrix in the presence of an organotin catalyst. Morphological, thermal, and mechanical properties of the rosin modified RTV silicone rubbers were characterized by scanning electron microscope (SEM), thermal gravimetric analysis (TG), universal testing machine, and dynamic mechanical analysis (DMA), respectively. Compared to the silicone rubber using tetraethoxysilane (TEOS) as the cross-linking agent, the RA modified RTV silicone rubber exhibited a significant enhancement in thermal stabilities and mechanical properties due to the strong rigidity and polar hydrogenated phenanthrene ring structure of rosin and the uniform distribution of RA in the RTV silicone rubber.