Abstract: The main purpose of this study was to conduct experimental investigation of particle separating by using the cyclone. A cyclone was designed with 10 cm diameters. Mud sample is pumped to the system with varied flow and concentration and the efficiency of system was determined. Obtain results showed that the removal efficiency was increased with speed of fluid and particle size and was 79 to 93.5% for particles over 144 μ. Results suggest cyclones can be considered as a suitable unit in separation of particles in water and wastewater treatment.