The invention discloses a multiferroic thin-film material of a layered perovskite structure and a preparation method thereof. The prepared multiferroic thin-film material is characterized in that bismuth, iron, cobalt, titanium and oxygen elements form a thin film, wherein a chemical formula of the thin film is Bin+1Fen-3-xCoxTi3O3n+3, Bi is bismuth, Fe is iron, Co is cobalt, Ti is titanium, O is oxygen, n is more than or equal to 4, n is an integer, and x is more than 0 and less than or equal to (n-3) / 2; meanwhile, thickness of the multferroic thin-film material is 400-1000nm, the multiferroic thin-film material is composed of platy particles arranged compactly, and the particle sizes of the platy particles are 20-300nm. The multiferroic thin-film material has excellent ferroelectric and ferromagnetic properties, a production process is simple and easy to learn, less equipment is required, a sintering magnetic field is low, a sintering phase formation temperature is low, and the preparation cost is low, so that the multiferroic thin-film material is beneficial to large-scale industrial production.