The invention discloses a Pt modified gradient Al coating and a preparation method thereof, and belongs to the technical field of high-temperature protecting coatings. The preparation method comprisesthe following steps: plating a MCrAlY bottom layer on a high-temperature alloy matrix by using arc ion plating; then plating a pure Pt layer on the MCrAlY bottom layer by an electroplating method, and annealing under the vacuum condition; and finally, plating a pure Al top layer on the surface by arc ion plating and carrying out corresponding annealing treatment to obtain the Pt modified gradientAl coating. The outer layer of the coating is rich in Al while the inner layer of the coating is rich in Cr, and the outer layer is a beta-(Ni, Pt) Al and PtAl2 phase. The Pt modified gradient Al coating has the advantages that the content of Al in the MCrAlY bottom layer can be increased remarkably, and the high-temperature-oxidation resistance of the MCrAlY bottom layer is improved; and the content of a Pt element of the coating and the thickness of the coating are controllable.