The invention discloses a silicon coated nano-titania-doped cement-based composite material. The silicon coated nano-titania-doped cement-based composite material contains cement, silicon coated nano-titania, silica fume, coal ash, sand, a water reducer and water. The invention further discloses a preparation method of the cement-based composite material. Experiment results show that the silicon coated nano-titania-doped cement-based composite material combines the advantages of titania and silicon dioxide and takes full advantage of the characteristics of toughening effects, filling effects, nucleation effects, volcanic ash effects and high strength and toughness of nano-titania and silicon dioxide, so that the rupture strength, compressive strength and durability of the silicon coated nano-titania-doped cement-based composite material are better that those of a silicon coated nano-titania-doped cement-based composite material. Besides, the silicon coated nano-titania-doped cement-based composite material further has electrical properties and can meet the requirements on multifunction and intelligence of structural materials in future.