Abstract: A method for preparing a platinum alloy catalyst using an oxide coating according to an embodiment of the present disclosure comprises: a first step of preparing a dispersion by mixing a commercial platinum catalyst and a transition metal precursor with a solvent; a second step of preparing a catalyst by putting an ultrasonic tip into the dispersion prepared through the first step and performing an ultrasonic process; a third step of performing a primary heat treatment process on the catalyst prepared through the second step; a fourth step of performing an acid treatment process on the catalyst that has undergone the primary heat treatment process through the third step; and a fifth step of preparing a platinum alloy catalyst by performing a secondary heat treatment process on the catalyst that has undergone the acid treatment process through the fourth step.