<p>For developing a PM filter for gasoline soot, it is necessary to consider that the exhaust gas temperature and filtration velocity of gasoline vehicles are expectedly higher than those of diesel vehicles. Moreover, gasoline soot is much smaller than diesel soot. Therefore, the better filtration efficiency for smaller particles is needed. So far, we are focusing on SiC sponges potentially applied for GPF. Its porosity is over 0.9, which is higher than that of the so-called wall-flow filter. In this study, we have simulated the flow with soot deposition by a lattice Boltzmann method (LBM), by changing the inflow velocity and the soot size. Two different sponges of SC68 and SC90 were used. These 3D substrate structures were obtained by the X-ray CT measurement. Results show that the initial pressure drop before the filtration becomes larger as the inflow velocity increases, but it is not simply proportional to the inflow velocity. Based on the distribution of the soot deposition region, the depth filtration and the surface filtration are observed. The smaller the soot size, the greater the amount of the deposited soot, with the thicker soot deposition layer. The pressure drop is increased at the higher inflow velocity and the smaller soot size. At the same period, SC90 shows the better filtration performance that can collect more soot. Thus, for optimizing the substrate structure, it is important to reveal the filtration process of the depth filtration and the surface filtration as well as the resultant pressure drop.</p>