The nanometric La2-xKxCuO4 oxide catalysts with K2NiF4-type structure were prepared by auto-combustion method using citric acid as a ligand and an adjusting agent of particle-size and morphology. The structures and physico-chemical properties of these perovskite-like oxides were examined by means of XRD, FT-IR, H2-TPR and chemical analysis. The catalytic activities for the simultaneous removal of soot and NOx were evaluated by a technique of the temperature-programmed oxidation reaction (TPO). In the La2-xKxCuO4 catalysts, the partial substitution of K for La at A-site leads to the increase of the concentrations of Cu3+ and oxygen vacancy. Thus, it enhances the catalytic activity for simultaneous removal of NOx and diesel soot, and the optimal substitution amount of potassium x is equal to 0.5 among these samples. T10, T50, T90 are 376, 438,487 ℃ and PN2 is 22%, respectively, for simultaneous removal of NOx and soot particulates over the La1.5K0.5CuO4 catalyst under loose contact conditions between the catalyst and soot.