The invention relates to a preparation method for a cerium-zirconium-palladium nanopowder catalyst. The preparation method comprises the following steps: dissolving a cerium source and a zirconium source in absolute ethanol, and adding P123 template agent to obtain sol; adding palladium nitrate; keeping constant temperature of 35DEG C and constant relative humidity of 40 percent, and performing evaporation induction to form gel; drying at the temperature of 100DEG C; calcining at the temperature of 400DEG C for 4 hours at the temperature rise rate of 1DEG C per minute; and ensuring that the atomic mole ration of cerium to zirconium is 8:2, the palladium loading quantity is 0.1 to 5 weight percent, and a ratio of the cerium source and the zirconium source to the absolute ethanol to the P123 is 10mmol:20ml:1g. The catalyst is suitable for catalytic elimination of CO in flue gas discharged by a catalytic cracking catalyst regeneration device and Co in tail gas of motor vehicles and has the advantages of large specific surface area, uniform distribution of noble metal active ingredients, high catalytic activity and thermal stability, and simple synthesis method; the temperature for complete catalytic conversion of CO can be greatly reduced; the consumption of noble metals is reduced; and the cost of the catalyst is reduced.