Recently, a diesel particulate filter (DPF) has been developed for the after-treatment of diesel exhaust gas. In simple explanation of DPF, it traps PM when exhaust gas passes its porous wall. However, since the filter would be plugged with soot particles to cause an increase of filter back-pressure, a filter regeneration process is needed. In this study, we simulated the flow with soot combustion by the lattice Boltzmann method (LBM). Here, a real filter was used in the simulation. The inner structure of the cordierite filter was scanned by a 3D X-ray CT technique. By conducting tomography-assisted simulation, we obtained local velocity and pressure distributions in the filter, which is hardly obtained by measurements. Especially, to consider the heat transfer to the solid wall of the filter substrate, the equation of heat conduction was solved, simultaneously. That is, the conjugate simulation of gas-solid flow was presented. Based on the temperature change and reaction rate in DPF, the heat and mass transfer in the filter regeneration process was discussed.