The invention discloses a BOPP matt film and a preparation method thereof. The matt film comprises a supporting layer and a matt layer, the supporting layer comprises components including polypropylene and an antioxidant, the mass of the polypropylene accounts for 99.8%-99.9% of that of the supporting layer, and the mass of the antioxidant accounts for 0.1%-0.2% of that of the supporting layer; the matt layer comprises components including polyethylene, polypropylene, a haze distribution modifier and an antioxidant, on the basis of the mass of the matt layer, the polyethylene accounts for 40-60%, the polypropylene accounts for 58.9-24.7%, the haze distribution modifier accounts for 1-15%, and the antioxidant accounts for 0.1-0.3%; and the haze distribution modifier is an ethylene-propylenecopolymer, an ethylene-butylene copolymer, an ethylene-hexene copolymer, an ethylene-octene copolymer, a propylene-butene copolymer, terpolymer or low isotactic polypropylene. A polyolefin material is added in a matt film production process as the haze distribution modifier, and thus, the uniformity of haze distribution of the matt film is improved remarkably.