The invention discloses a purification method of NiO nanocube particles synthesized with a laser method. The purification method achieves separation and purification of nickel particles in different sizes in a NiO nanocube particle mixture prepared with the existing laser method. The purification method comprises the steps that the nickel particles with larger particle sizes in a synthetic product are removed with a millipore filtration method; the nickel particles with the smaller particle sizes in the NiO nanocube particles are removed through iron absorption while a stirrer is used for stirring; low-temperature drying is conducted; moisture is removed; the high-purity NiO nanocube particles are obtained; and a product recovery rate is 97.5%. The purification method is simple in technology, low in equipment requirement, and high in product purity, and does not generate toxic waste liquid, and the nickel particles in different sizes can be recycled. The NiO nanocube particles purified with the purification method can be applied to the fields of catalysis, electrode materials and the like.