The invention relates to the field of photocatalysis, and particularly relates to a visible-light-driven photocatalyst for degrading dye in wastewater, and preparation and application thereof. The visible-light-driven photocatalyst for degrading dye in wastewater is characterized in that mesoporous silicon dioxide of which the framework contains Ti atoms is used as a carrier, the mesoporous silicon dioxide carrier carries graphitic carbon nitride, and bivalent Cu ions are doped on the graphitic carbon nitride, wherein the graphitic carbon nitride with the doped cupric ions serves as a main catalyst, and the element Ti serves as a cocatalyst. The Ti atoms contained in the framework of the mesoporous silicon dioxide directly react with H2O2 in a photo-Fenton-like system to produce hydroxyl free radicals, thereby obviously improving the photo-Fenton-like reaction activity. The photocatalyst provided by the invention catalyzes degradation of methyl orange and/or rhodamine B in wastewater, and degradation can be performed at room temperature under the irradiation of visible light, thereby enabling the photocatalyst to have the advantages of mild reaction conditions, low cost and easy implementation; and the photocatalyst can be easily regenerated, and still has excellent photocatalytic performance after being regenerated many times.