The Aim of this paper is to study the properties of spin transport for ferromagnetic graphene superlattice unit cell junction taking into account the induced ac-field at different frequencies. Transfer matrix method is used for both spin alignments to calculate the conductance in terms of which spin polarization and giant magneto-resistance are also expressed. The results show that an oscillatory behavior is strongly exhibited by the three calculated quantities. These oscillations could be explained by the mutual effect between the magnetic field of the ferromagnetic insulator EuO, which causes spin filtering, and the induced photon energy of applied ac-field. The present research might have a scientific potential in the design and understanding of graphene superlattice based spin filters by optimizing the different parameters studied in this paper.