The invention discloses a waterproof carbon paper chromogenic layer coating. The coating comprises, by weight, 3-5 parts of light calcium carbonate, 2-4 parts of calcined kaolin, 1.5-1.8 parts of activated clay, 2-4 parts of corn modified starch, 0.6-0.8 parts of carboxymethylcellulose sodium, 3-5 parts of paraffin, 0.5-0.7 parts of an emulsifier, 5-8 parts of styrene-butadiene latex, 3-5 parts of polyamine polyepoxy resin, 0.5-0.8 parts of a composite dispersant, 1-2 parts of dimethicone, 3-5 parts of carboxylic styrene butadiene latex and 1.2-1.5 parts of titanium dioxide. Light calcium carbonate with fine and uniform particle size is easy to obtain, is safe and environmentally friendly, and has no pollution to human bodies or environment; the composite dispersant allows the prepared coating to have low viscosity, few bubbles and low dynamic surface tension and to reach below 40dyne; and activated clay is applied to make the coating have the advantages of fast chromogenic speed, high whiteness and uniform hue and to make a coat obtained through using the coating have smooth and flattened surface, high glossiness, and good and lasting waterproof effect.