Perovskite Solar Cells have very low absorption in the near-infrared region. In this paper, in order to enhance the absorption in this region, a new technique has been presented based on multiple excitations of plasmonic modes through the gratings on the backside of the cell. Gratings on the backside of the active layer lead to absorption enhancement by exciting localized surface plasmons and light scattering, and since the resonance of surface plasmons is highly dependent on the dimensions of the gratings, the resonance wavelength can be adjusted by accurately determining the dimensions of the gratings. In order to simultaneously increase in several wavelengths, multiple gratings have been used on the backside of the cell. In using multiple gratings, the absorption in the near-infrared region has been increased many times by choosing the appropriate dimension of gratings. The highest average absorption of 68.46% has been achieved using five gratings which is a 50% increase compared to the structure without gratings. The simulation results under incident angles from 0 to 85 degrees indicate that gratings enhance light absorption up to an angle of 45 degrees. Meanwhile, the structure with five gratings degrees has an average absorption close to 70% up to an angle of ±45 degrees and is not sensitive to the incident angle. These multiple nanostructures have the ability to trap more light inside the active layer and thus promise a high-efficiency solar cell.