The important parameters in mineralization treatment of petroleum refinery wastewater by electro-Fenton process were successfully simulated by Computational Fluid Dynamics (CFD). The effects of H2O2/PRW (ratio of mole of H2O2 per petroleum refinery wastewater volume), H2O2/Fe2+ molar ratio, current density, pH and reaction time were numerically investigated. Materials distribution in the electrochemical cell was studied and CFD results demonstrated that distance between electrodes had no significant effect on the Chemical oxygen demand (COD) removal. Furthermore, the results were compared with the experimental data. The simulated data showed that maximum COD removal was around 82.55% at H2O2/PRW of 0.04, H2O2/Fe2+ molar ratio of 2.75, pH of 3.5, current density of 52.5 mA/cm2 and reaction time of 90 min while the experimental data obtained from the literature showed maximum COD removal of 77% in the same operating conditions. The simulated data showed a good agreement with the experimental ones.