This paper presents an experimental study on oxidation of diesel paticulate matter (PM) and aims at investigating the characteristics of PM oxidation. The experiments were performed over a Cu0.95K0.05Fe2O4 catalyst which is attributed to a spinel type metal oxide. The effects of O-2 on PM oxidation as well as on NOx reduction were studied and the roles of O-2 in PM oxidation and in NOx reduction, respectively, are discussed. During the temperature-programmed oxidation of PM, SOF oxidation and soot oxidation lead to two CO2 peaks at different temperatures. It was found that the presence of O-2 benefits PM oxidation but suppresses the reduction of NOx into N-2 by consuming the soot. This study revealed that the appearance of PM oxidation is different from that of soot oxidation. The mechanisms on PM oxidation and NOx reduction are discussed.