Thehydro cyclone is an important and popular industrial apparatus to separate by centrifugal action disperse solid particles from a liquid suspension fed to it. It has been widely used in industry, particularly in the mineral and chemical processing industry because of its simplicity in design and operation, high capacity, low maintenance and operating cost as well as its small physical size. In general how a hydro cyclone works is included, providing a background to discuss a process and hydro cyclone geometry variables. The CFD technique popularly in process design and predicting equipment performance of hydro cyclone under a wide range of geometric and operating condition by using ANSYS.CFX; it also offers an effective way of design and modeling of hydro cyclone.