Abstract-Glass fiber reinforced polymers (GFRP) bars are non corrosion materials, their tensile modulus relatively are lower compared to steel reinforcement. A total of three beam specimens (GB1~GB3) were simulated under four-point bending. The main parameter's studies were the amount of GFRP reinforcement ratio, concrete strength, concrete cover thickness and the height of beam cross-section. To study the influence of these parameters on the flexural behavior of GFRPs concrete beams, ABAQUS Finite-element software was used. The results showed that; there are clear improving of bearing capacity when the reinforcement ratio and height cross-sections of the beam were increased, but increase of concrete strength lead to increases as the bearing capacity, but this increased is limited by concrete compressive failure strain of reinforced concrete beams, while increasing the concrete cover thickness, lead to a negative efficient of GFRP reinforced concrete bearing capacity.