An improvement of the internal geometry of a three-dimensional control valve with complex geometry is carried out by the authors, in order to obtain a better hydrodynamic behaviour of the flow through the valve. A Computational Fluid Dynamic simulation is used to model it and to avoid the manufacture of the intermediate geometries. This research is a continuation of a previous study where the model and procedure for analyzing a control valve using CFD were validated using experimental data. The characteristics of this model were carefully defined and a standard k-ε turbulence model was finally chosen. The final CFD model used predicts accurately the flow behaviour through the valve in both open and pressure regulation valve situations. Cavitation is also investigated in order to obtain the most affected areas inside the valve.