Abstract In this work, a three-dimensional mathematical model is established to investigate the flow and the heat transfer of the combustion process and the distribution characteristics of temperature field in the wall-flow in porous media of the wall-flow diesel particulate filter (DPF) based on the Field Synergy Theory (FST). The results indicate that there is the smallest temperature uniformity coefficient in wall-flow DPF when the inlet velocity is 36 m/s. And at first, the microwave assisted regeneration temperature increases and then decreases as the exhaust temperature rises which is affected by the exhaust temperature. The data indicate that the inlet pressure can change the angle between velocity vector and temperature gradient, which leads to the change of synergy degree of the velocity field and temperature field. When the inlet pressure is 0.08 MPa, there is an optimal synergy degree with the maximum average temperature.