A novel three-product hydrocyclone screening device (TPHS) has been successfully developed. Through systematic research and experimentation, this equipment demonstrates superior efficiency and throughput compared to conventional hydrocyclones in coal slurry classification. While improvements in classification efficiency and processing capacity have been achieved, insufficient exploration exists regarding the unique screening-through classification zone. Therefore, this paper establishes a multi-stage hydrocyclone screening-through model (MHS) to investigate its flow field and classification characteristics. This study employs Fluent and CFD-DEM simulations to investigate the swirl flow field characteristics, examining the flow patterns within the cyclone screening structure and its impact on particle motion. Results indicate: - High turbulence intensity and uneven velocity distribution in the first flow channel significantly affect fluid velocities within the cyclone tube. Complex turbulence within the first screen aperture affects subsequent particle screening, prolonging the screening process. At a rotational radius R=75, radial forces dominate the flow field, facilitating particle screening in the separation zone. Under vortex influence, particles exhibit three distinct motion trajectories within the screening region.