Strengthening of structures using external pre-stressed Carbon fiber reinforced polymer systems have proven to be an effective process as system strengthen the structural capacity and decrease cracks and deformability. Three dimensions finite element model using ANSYS program is set up to study the impact of composite beams strengthened using externally pre-stressed Carbon fiber reinforced polymer tendons under flexural behavior. Studying parameters like pre-stress level, tendon material and tendon profile elevated from the bottom surface of steel beam flange considered under static loading. Consequences of the parametric study will give reasonable guidelines for the designers. The accuracy of the 3-D model is verified with the available experimental data. End from the finite element model and design suggestions are given.