Recently, yttrium iron garnet (Y3Fe5O12, YIG) ferrite thin films have attracted great interest within the scientific community, which are motivated by their possible applications in spintronic devices [1]. For spintronic devices, the essential step is to fabricate the ordered arrays of nano magnets on appropriate substrates, as required by the emerging information technologies such as ultrahigh density storage devices, sensors and magnetic random access memory devices [2]. Although some reported the metal-based patterned magnets fabricated with modern lithography techniques in recent years, very few reports on patterned oxide magnets have been found, which is probably due to the lack of a suitable fabrication process for high-density and large area nano dots arrays.