One of the most important issues in the design of photodetectors is absorption efficiency. An innovative structure of a graphene-based photodetector consisting of an array of plasmonic nanostructures is proposed. Surface plasmons resonance occurs near the plasmonic nanostructures, enhancing the interaction between light and graphene; this gives rise to a strong light absorption. The numerical analysis results show that the proposed photodetector has a total absorption efficiency of 87.7% and a photocurrent of 1000  μA. Also, this structure exhibits the responsivity of 2053  mA  /  W and the bandwidth of 25.17 GHz at the wavelength of 1.55  μm. The other outstanding features of this design are low power consumption and being CMOS compatible. The results reveal the superiority of the proposed photodetector performance in terms of responsivity and optical bandwidth in comparison with the other existing designs.