A dynamic filtration model of the gasoline particulate filter(GPF) was developed，considering both pore and wall scales，with the addition of radial porosity heterogeneity in the porous media. The impact of internal structural changes in the GPF on particle filtration performance was investigated from the perspectives of filtration mechanisms and microscopic size. It is found that the primary filtration mechanisms in GPF are Brownian diffusion and interception，which correspond to the filtration of small particles(＜30nm) and large particles(＞200nm)，respectively. When the mean pore size in the GPF decreases or the pore size variance increases，the proportion of collectors with diameters smaller than 10μm increases. This results in a higher number of collectors achieving more than 50% filtration efficiency for particles in the range of 10—300nm，thereby enhancing the total filtration efficiency of the GPF. After 20minutes of particle filtration，the filtration efficiency increases and the particles adhere to the area of lowest porosity，where the porosity reduces. However，the efficiency of Brownian diffusion and interception slightly decreases，indicating that porosity plays a dominant role in influencing filtration efficiency during the dynamic filtration process.