Abstract: A review on the perpendicular magnetic anisotropy of Co/Pt multilayers and Co_xPt_1-x (x≈0.25) alloy films was presented. For Co/Pt multilayers, the perpendicular magnetic anisotropy is mainly resulted from the reduced symmetry and the hybridization between Co and Pt d orbits at interface. The alloying and roughness at interface do not benefit the perpendicular magnetic anisotropy. The effect of strain on the perpendicular magnetic anisotropy of the multilayers is not clear yet. For Co_xPt_1-x alloy films, the segregation of Co and the anisotropy of Co’s orbital magnetic moment and the number of Co-Co pairs were observed. These mean that the perpendicular magnetic anisotropy of the alloy films originate in some local composition modulating structure similar to Co/Pt multilayers. It is found that the perpendicular magnetic anisotropy of Co_xPt_1-x (x≈0.25) alloy films kept unchange while the grain size increased with the film thickness. It suggests that the chemical ordered local structure resulting in the perpendicular magnetic anisotropy is in equilibrium state.