The invention discloses a method for preparing an automobile exhaust catalyst. The method comprises the steps of (1) mixing praseodymium and cerium, wherein the molar percent content of praseodymium is roughly equivalent to that of cerium; (2) doping 0-10% of zirconium and 0-10% of yttrium on the basis of the step (1); (3) immediately doping 0-2% of noble metal after doping zirconium and yttrium and mixing gamma aluminum oxide, thereby forming a mixed oxide, wherein the amount of mixed gamma aluminum oxide is 0.1-1mol; (4) coating the surface of a monomer carrier with the mixed oxide formed in the step (3). The mixed oxide prepared through the method has high specific surface area and high oxygen storage capacity in a low-temperature environment, and the surface area stability of the mixed oxide is increased through zirconium and praseodymium, so that the preparation cost of the exhaust catalyst for reducing cold start discharge through a three-way catalyst and the like is greatly reduced; and the mixed oxide prepared through the method coats the surface of the carrier and the weight of the mixed oxide is about 30%-50% of that of the carrier.