A series of perovskite-type oxides and derived Ag catalysts were prepared, and characterized by N-2-adsorption, X-ray diffraction and X-ray photoelectron spectroscopy. The influences of pretreatment and Ag loading on catalytic activity for diesel soot oxidation were also investigated. Prereduction resulted in a decrease in catalytic activity. An increase in activity with Ag addition was observed, especially with more than 5% Ag loading. This catalyst could be a promising candidate for the catalytic elimination of diesel soot.