The invention discloses a water-based color-brushing agent and a preparation method thereof. The water-based color eraser is mainly formed by soaking, fine grinding, filtering, stewing, extruding and uniformly stirring bean calcium carbonate (large white powder), calcium sulfate (gypsum), a preservative agent, water, and the like. According to the invention, the technical problem to be solved is that the water-based color-brushing agent which utilizes the characteristic of the characteristic of high penetrability of leguminous plant resin, has the characteristics of reasonability in compound design, nontoxicity, odourlessness, fast drying, good permeation filling ability, high definition, higher stereoscopic impression, good environmental friendliness, harmlessness on human bodies, and the like, can be used by being matched with various paints, is not discolored after being used for a long time, is slightly superior to the decorative effect of the traditional color-brushing agent and a coloring agent on spraying effect and has better environmental friendliness and safety during usage is provided.