In this work, Co 2D antidot arrays with well-ordered hexagonal holes ranging in size from 1.3 to 6.2 μm were fabricated by colloidal crystal template method. The geometry configuration and magnetic properties of the samples were investigated. An enormous increase in coercivity and squareness, as compared with the corresponding continuous film, was observed. Magnetic properties of Co 2D antidot arrays showed a close dependence on pore diameter. According to geometric calculation, the effect of the pore diameter on magnetic properties was also discussed. The Co 2D antidot arrays obtained by this method are promising candidates for high-density information storage.