In recent years, many efforts are increasingly being made to conserve the natural environment with enhancedemission standards and air quality standards. Also there are various methods necessary to be researched to minimize theemission of air pollutants. In particular, boilers of industrial facilities are major portions of the air pollution. The frontduct which needs to be designed to reduce the gases to the electrostatic precipitator requires a bent tube, areduction/extend tube and an auxiliary equipment, that is, a guide vane. This paper proposes an optimum design of theguide vane by a case study for electrostatic precipitator’s flow uniformity. The operating conditions of this study are asfollows: BMCR (Boiler Maximum Continuous Rate) and MGR (Maximum Guaranteed Rate) are 75%, 50%, and 30%;turbulent fluid dynamics model is based upon K-ε formulation. Presentation of the computed motion of particles is foundto be quite useful to predict the precipitator performance by use CFD (Computational Fluid Dynamics).