The numerical simulation of the fluid flow and particle dynamics is presented by CFD techniques to characterize the performance of the three types of standard cyclones. The three types of cyclones named 1D3D, 2D2D and 1D2D. The length of cylindrical part of the body is equal to 1,2 and 1 times of the body diameter, respectively; and the length of the conical part is 3, 2 and 2 times of the body diameter. The Reynolds averaged Navier-Stokes equations with Reynolds stress turbulence model (RSM) are solved by use of the finite volume method based on the SIMPLE pressure correction algorithm in the computational domain. The Eulerian-Lagrangian computational procedure is used to predict particles tracking in the cyclones. The velocity fluctuations are simulated using the Discrete Random Walk (DRW). The dependency of cyclone characteristics on its diameter is investigated and D-50 (Cut-Point) is calculated for different Particle Size Distributions (PSDs). The numerical results are compared with the experimental data and the theoretical model and good agreement is observed. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.