Strengthening using a steel fiber-reinforced concrete (SFRC) jacket is one of the most important used strengthening systems recently because of its attractive solution for the performance of beams in shear. The main objective of this study is to evaluate the structural performance of RC beams strengthened with SFRC jackets taking perfect bond between them using a three-dimensional (3D) finite element (FE) model. To check the accuracy of the proposed model, the numerical FE results were compared with the results of previous experimental researches. A parametric study was carried out to study the effect of both the volume fraction of fiber and the thickness of the jacket. The analysis of results shows a good agreement with the corresponding experimental measurement. The results of the parametric study have proved that increasing the volume fraction of fiber and thickness of the jacket, increases the stiffness and shear capacity and decreases mid-span deflection at failure.