The invention relates to a water-based coating. The water-based coating is prepared form the following raw materials in percentage by weight: 52 to 55 percent of water, 0.5 to 0.7 percent of sodium dodecyl sulfate, 20 to 25 percent of methyl methacrylate, 3 to 4.5 percent of butyl acrylate, 0 to 2 percent of ethyl hexyl acrylate, 1 to 1.5 percent of acrylic acid, 10 to 15 percent of butyl methacrylate, 1 to 2 percent of butyl maleate, 0.6 to 1 percent of ethyl acrylate, 0.4 to 1 percent of itaconic acid, 0.8 to 1 percent of ammonia water, 0.1 to 0.2 percent of antifoaming agent, 0.05 to 0.1 percent of sodium acetate, 0.1 to 0.2 percent of preservative and 0.1 to 0.2 percent of potassium persulfate. The invention also provides a method for preparing the water-based coating. The water-based coating of the invention is innoxious and has a small amount of environmental pollution; and a coating layer formed by coating has the advantages of high brightness, toughness, excellent anti-explosion performance, excellent subsequent processing performance, capability of stamping gold rapidly and efficiently and good gold stamping effect.