© 2017 Taiwan Institute of Chemical Engineers The effect of the particle mass loading (1.6–115.3 g/m3) on the performances of a cyclone separator is studied by two-way coupling CFD simulation and experiments. The increasing of the particle mass loading enriches the particles at the wall region. At lower inlet air velocity, the separation efficiency increases with the increasing of the particle mass loading due to the larger particle sweeping effects and the aggregation of smaller particles. The full elastic particle–wall collision and the perfect dust box bottom collection assumptions cause CFD simulation overpredicting the separation efficiency of smaller particles. A partial elastic particle–wall collision assumption overcame the problem and reduced the calculated separation efficiency. Our CFD simulation can reasonably predict the separation efficiency at different particle mass loadings.