Highly ordered Co antidot arrays with different pore diameters (1.0，2.1，3.0，4.1, 5 μm) and the same thickness were prepared via sputtering Co into the gaps of PS colloidal crystal templates with different sputtering time. The structure and magnetic properties of Co antidot arrays were characterized by SEM, AFM, XRD and VSM. It is found that the coercivity and remanence ratio of Co antidot arrays are up to 253.18×10-4 T and 0.85, respectively, and they are 3.4 and 2.3 times larger than those of Co films, respectively. Moreover, with the increase of the pore diameter, the coercivity and the remanence ratio decrease gradually. The results of theoretical analysis indicate that the excellent magnetic characteristics come from the shape anisotropies induced by the structure itself, and the change of the shape anisotropies caused by pore diameter and pore spacing results in the change of the magnetic properties.