Abstract: With hightemperature alumina carrier and high performance rareearth composite oxide as raw materials,different amountofsubstance and mass purified catalysts with Pt/Pd/Rh noble metals active components were prepared.Lightoff temperatures and airfuel ratio characteristics of catalysts were studied,and results indicated that high performance&nbsp; cerium zirconium compsite oxide modified with praseodymium can widen airfuel ratio window and reduce use level of noble metals;catalysts with Pt/Rh,Pd/Rh and Pd,possessed good performances in purifying exhaust gas of compressed natural gas(CNG)vehicles;Pd and Pd/Rh catalysts had the best activity at lowtemperature.All the prepared catalysts had good activity.<BR>