In this paper, a new method of nanoparticle preparation by laser ablation of tiny wire is reported. Moreover, an archetypal equipment is designed and manufactured. In experiments, magnetism γ-Fe2O3 nanoparticles are prepared by laser ablation of 0.5 mm diameter pure iron wire in a mixture of nitrogen and oxygen. The prepared γ-Fe2O3 nanoparticles are basically spherical in shape and form chain-like structure because of their magnetism. Besides, the prepared nanoparticles are uniform in granularity with little agglomeration and the average diameter is about 19 nm. For comparison, preparation of γ-Fe2O3 nanoparticles by laser ablation of Fe bulk material is also conducted under the same condition. Laser ablation of iron wire can realize explosive evaporation of the target, which is different from that laser ablation of bulk iron target in mechanism and may cause the production increase greatly. The production rate of γ-Fe2O3 nanoparticles by laser ablation of iron wire is about 1.8 g/h under 400 W laser output, almost 6 times as much as that by laser ablation of bulk iron target under the same condition.