The aim of this work is to design a cyclone separator, which could reach the highest separation efficiency for fine and low-density particles (110 mu m) and air-flow rates between 10 and 100L/min. The first part of the study is dedicated to the design, thanks to cyclone software developed by PROGEPI, Nancy, France. It uses classical models and does not take into account the dispersed phase fraction, but allows giving a first approach of the cyclone geometry. Results lead to a Lorenz geometry and pressure drop lower than 10KPa for 100L/min. The separation efficiency is never lower than 75% for 2-mu m particles at 50L/min. In the second part, a computational fluid dynamics study via fluent is conducted in order to determine the performances of the device, thanks to the particle trajectories simulations. Results show that for the higher flow rate (100L/min), a separation efficiency of 60% is reached for 1-mu m particles. For a lower flow rate (10L/min), this cyclone is not satisfying because no 1-mu m particles are separated. This study shows that these two approaches are quite complementary in order to reach the most accurate design.