Parametric study of beams with reinforced with FRP rebar is conducted in this study. Using ABAQUS program, the finite element analysis model is set and calibrated with the experimental results which have been conducted by the authors. The employed design parameters are reinforcement ratio, elastic modulus of rebar, and concrete strength. The obtained results from FE analysis are investigated in terms of normalized beam stiffness. In particular, the effect of reinforcement ratio on the flexural stiffness is investigated with comparing with the model code specified on ACI 440. From the analysis results, the reinforcement ratio in beam is the first parameter affecting on the beam stiffness. In addition, its effect could be increased with higher concrete strength.