The influence of copper substitution in La0.8K0.2CuxMn1-xO3 on its catalytic performance for simultaneous removal of NOx and soot under oxygen rich conditions was investigated. A series of catalysts was prepared and then characterized by XRD, SEM, BET, and XPS. The temperature programmed reaction (TPR) method was used to evaluate the catalytic performance of the catalysts. XRD results show that the partial substitution of Cu for Mn promotes the formation of perfect perovskites. SEM and BET results demonstrate that appropriate copper substitution enhances the porosity and increases the specific surface area, leading to conditions which are favorable for heterogeneous catalysis. XPS results indicate that a fraction of the Mn3+ is converted to Mn4+ on the addition of low levels of Cu. By correlation of the physicochemical properties and the catalytic performance, a large specific surface area, high porosity, high content of Mn3+ and synergistic effects of Mn3+ and Cu2+ are seen to favor the simultaneous catalytic removal of NOx and soot.