Particle classification is of significant importance in industry. There have been long and lasting efforts to have a better design, optimized operation and scale-up of various relevant processes, however, our understanding is still far from complete, due to the involved very complex processes. This area is designed to report the latest advances in the studies on particle classification, including but not limited to cyclone & hydrocyclone, filtration, emerging cleaning techniques for particle separation with respect to environmental issues and particles sorting, all experimental, numerical and theoretical studies are invited in the area of particle classification.