This paper is to study the modeling and computing method for fibrous filters with image effect based on the previous studies. It takes the exhaust aerosol of diesel engine as an even floating flow composed of exhaust and particulate as without effect of electrical field force and the particulate flow along with other gas phase components. As with effect of electrical field force, the particulate deviate from other gas phase components and at the same time a resistant force from the gas components is added on it. This paper set up a model for calculating the flow and the electric field, as well as the capture efficiency of a single fiber model. The calculated capture efficiency is agreed very well with the experimental data.