As catalytic materials, nanometer rare earth perovskites LaMnO3 were prepared by NaOH-Na2CO3 coprecipitation, followed by supercritical drying, vacuum drying and air drying respectively. The effect of drying processes was studied on the catalyst performance through XRD, TEM, SEM and BET analysis. The results demonstrated that about 30 nm LaMnO3 particles could be prepared by three drying processes respectively. The catalyst materials LaMnO3 dried in vacuum presented the largest specific surface area as 28.71 m2·g－ 1. Compared to the catalyst prepared by dipping cordierite directly in the salt solutions, nanometer LaMnO3 showed better catalytic activity. The light-off temperatures for CO and HC oxidation were both lowered by 100℃ , and its NOx conversion could be up to 100％ at 570℃ .
