The invention relates to a water-based ink and a preparation method thereof, especially to an environment-friendly type water-based intaglio ink used for package printing and a preparation method thereof. The ink is prepared by mixing epoxy acrylate composite emulsion, pigments, deionized water, ethanol, triethylamine, wax powder, a wetting dispersant, an anti-foaming agent, a levelling agent, a thickening agent and a film forming auxiliary agent according to a certain mass ratio, wherein, the epoxy acrylate composite emulsion is prepared by modifying acrylate emulsion with an epoxy resin and allowing the epoxy resin and acrylate to organically bind together, has the advantages of good adhesion, thermostability, good chemically-resistant properties and the like and has a certain application value when used as a binder for a water-based ink. The water-based intaglio ink in the invention is applicable to package printing in the field of flexible package which mainly relates to packaging of tobacco, liquor, foodstuffs, beverage, medicines, daily chemical articles and the like; the ink is nontoxic, non-combustible and non-explosible, has no pungent smell, accords with environmental protection requirements, and has a very promising prospect.