Based on the air-flow characteristics of diesel wall-flow particulate filter, the mathematical model of loading process for the wall-flow filter was proposed. In this model, the porous wall was assumed to be composed of numerous spherical collectors. The effects of the exhaust-flow characteristic and the structural parameter of filter on the over-all properties of filter were analyzed. The results showed that decreasing exhaust-flow and increasing volume of filter optimize the characteristics of filtration and flow-resistance. Decrease in the ratio of length to diameter of filter optimize flow-resistance, whereas has no influence on filtration. Increment in wall thickness optimizes filtration, whereas deteriorates flow-resistance. Exhaust temperature and channel width both have a minor influence on both filtration and flow-resistance. The experimental results verified the accuracy of mathematical model. 