The invention belongs to the field of preparation of flue gas denitration catalysts and particularly relates to a manganese series-loaded and titanium-doped silicon nanotube SCR (Selective Catalytic Reduction) catalyst and a preparation method thereof. A titanium-doped silicon nanotube is used as a carrier, and manganese oxide is used as an active substance and is loaded on the titanium-doped silicon nanotube, so as to obtain the manganese series-loaded and titanium-doped silicon nanotube SCR catalyst. The invention also discloses a synthetic method of a titanium-doped silicon nanotube. The silicon nanotube has greater specific surface area, so that the dispersity of the active substances on the surface of the carrier is remarkably improved; the titanium-doped silicon nanotube provides more acid sites in a catalytic reaction process, so reaction active sites are increased, reduction temperature of a catalyst is lowered, and the catalyst is enabled to have good low-temperature activity and stability; the titanium-doped silicon nanotube is used as an active carrier, so that the catalytic reaction is favorably performed, and an active temperature window for selective catalytic reduction of the active carrier is widened.