This study focused on the preparation and characterization of silicon–acetylene resin by means of grafting functionalized mesoporous silica. (3-Aminopropyl) triethoxysilane was grafted to silica surface through the hydrolysis reaction to yield mesoporous silica functionalized with (3-Aminopropyl) triethoxysilane (MA). These MA nanoparticles were transferred to the chain of silicon–acetylene resin, poly(m-dietheynylbenzene-methylsilane) (PSA) to yield PSA-g-MA, with the help of the reaction of hydrochloric acid removal. PSA-g-MA was totally characterized by Fourier transform infrared spectroscopy, energy dispersive spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscope, transmission electron microscope, and nuclear magnetic resonance, which certified the success of silica modification and functionalized nanoparticles grafted to chain of PSA. The char content of PSA-g-MA reached to 45% at 1000°C under air atmosphere, and the residual weight was increased by nearly 10%, compared with the unmodified PSA.