LaNiO3 and LaCoO3 perovskite catalysts for simultaneous removal of nitrogen oxides and diesel soot were prepared by sol-gel method. The results indicate that LaNiO3 catalysts exhibited excellent catalytic activities for soot and NOx, which could decrease the soot combustion temperature tm by 216 ℃ and enhance the NO conversion efficiency by 104% as compared with those of non-catalysed reaction. It was thus assumed that diesel soot undergoes catalytic combustion reaction over perovskite-type catalysts through two routes: at relatively low temperatures, diesel soot is oxidized by the NO2 intermediate generated during NO oxidation reaction, and at high temperatures, it is oxidized by both NO2 and O2.