Three-dimensional random model of the pleated air filter media was built based on the actual melt blown fiber, and its microstructure was established considering a series of parameters, including pleated angle, layer, diameter, number of fibers, curvature, and so on, which had dynamic control of the pleated air filter media. The established model was basically similar to the actual electron microscope image of filter media. On this basis, the filtration characteristic of the pleated air filter media in the dust filtration stage was simulated using CFD?DEM coupling method, and the simulation results were compared with the relevant empirical correlations. The results show that the error between the simulation results and the empirical correlations is less than 10%, which indicates that the calculation based on CFD?DEM coupling method was feasible. In the dust filtration stage, the pressure drop increases nonlinearly with the increasing number of deposition particles at the same inlet gas velocity. The increased pressure drop increases with the increase of filtration time under different inlet velocities, the maximum increased pressure drop (0.214 Pa) appears at 0.6 m/s of the inlet gas velocity and the minimal increased pressure drop (0.133 Pa) appears at 0.4 m/s of the inlet gas velocity. The phenomenon of the particles’ deposition and agglomeration is obvious when the filtration time, T is 3.216 ms, and this phenomenon is more apparent in the penetrated region of fibers, which also indicates that the arrangement of fibers have significant influence on the deposition of particles.