Electronic structure and magnetism of Fe_n/Cr_n superlattices(SL) with various layer thickness(n=1,3,5) are studied using a full-potential linearized augmented plan-wave(FLAPW) method within a density functional formalism. It is shown that ferromagnetic state is a preferable phase in the ground state and the intrinsic spin density wave length is about 2 monolayers(ML). The magnetic moment of Fe layer is slightly modified by an intelvening Cr layer, and becomes stronger with the increase of n. The direction of Cr magnetic moment alternates layer by layer. An antiferromagnetic coupling hetween interfacial Fe and Cr layers is observed. There is a moderate hybridization between d-states of Fe and Cr atoms near Fermi energy.