This work aims to investigate, numerically, the impact of different geometrical parameters on pressure drop and tangential velocity in a cyclone separator. These parameters are the size of the rectangular cross-sectional inlet area, shape of the inletcross-sectional area, and mass flow rate. Different shapes of inlet cross-sectional area were chosen to be either rectangle (standard), circle, or ellipse. In this work, the impact of different turbulent models is tested first. These models are shear stress transport model (SST) k-ꞷ and k-ɛ which are compared with a laminar case (without any turbulence model). The cases with and without turbulence model are validated with available reference data. It has been found that the k-ɛ model agree well with the reference data. The larger inlet rectangular cross-sectional area leads to higher ratio of static pressure between the center of the cyclone and edges. On the other side, the tested range of mass flow rate (0.04, 0.08 and 0.16 Kg/s) to known effect this parameter in the static pressure and tangential velocity inside the cyclone. Furthermore, the static pressure and the tangential velocity have been observed in the case with ellipse cross-sectional inlet compared with that of rectangular- and circularcross sectional area.