Retrofitting structures with the use of fiber reinforced polymer (FRP), is an acceptable method in many parts of the world these days. This is because of good resistance and less effort. The other advantage of this method is the possibility of retrofitting without changing the appearance and size of the structure. Among the variety of structures, reinforced concrete structures and concrete beams are considered more for retrofitting with these materials. However, retrofitting a structure using externally bonded method, leads to use about 20 to 30 percent of capacity of FRP material. And this method will not show much improvement in serviceability state. The way has been proposed in recent years to solve these two major problems, is prestressing FRP before attaching it to the tensile side of the beam. The most common failure mode of reinforced concrete structures strengthened with FRP is premature debonding that is brittle and non-economic fracture. If FRP used in prestressed state, the occurrence of this type of failure will be more likely. So a proper solution to prevent premature debonding should be considered. Some methods have been proposed to prevent debonding, including using mechanical anchorage, U-shaped FRP plates and grooving methods. This study investigates the effect of using prestressing FRP strip on bearing capacity, ductility and capacity utilization percentage and studying the effect of grooving on behavior of beams strengthened with this method. For this purpose, first, several beam specimens with different conditions were modeled by using the finite element software ABAQUS. After comparing with experimental results and providing a proper model, failure modes, ductility, energy absorption, bearing capacity and ultimate deflection of samples were examined. For this purpose, 50 reinforced concrete beam specimens with the dimensions of 200×300×2700 mm were modeled. It can be concluded that the method of prestressing, increases the bearing capacity and reduces the ductility. This method can increase the capacity utilization percentage of FRP materials instead. Also using grooving method can improve flexural behavior of concrete beams strengthened with prestressed FRP strips. It is worth mentioning that grooving method in some cases can completely control premature debonding of prestressed FRP strips. Keywords : Fiber Reinforced Polymer (FRP), prestressing, nonlinear finite element analysis, ABAQUS, Grooving