The invention relates to a nanometer water-based UV ultraviolet curing lacquer which contains the following components: 65-80 parts of waterborne polyurethane dispersion agent, 0.4-1 part of de-foaming agent, 0.5-1.5 parts of wetting agent, 0.5-1 part of levelling agent, 0.1-3 parts of nanometer additive, 2-3 parts of water-based photo-initiator, 0.2-1 part of thickening agent, 3-5 parts of coalescing agent and 2-30 parts of water. The nanometer additive is one or two of nano-crystalline cellulose crystal and nanometer aluminum oxide. The invention further provides a preparation method for thelacquer. The nanometer water-based UV ultraviolet curing lacquer provided by the invention has high hardness, toughness and abrasion resistance, is a water-based environment-friendly product and is suitable for the coating of various high-end indoor wood furniture and indoor wood floor.