The invention discloses a vapor permeation-resistant coating for a chemical pump. The vapor permeation-resistant coating is prepared from the following components: isopropanol, glycerin alkyd resin, sodium carboxymethylcellulose, polydimethylsiloxane, styrene-acrylic emulsion, methylbenzotriazole, organobentonite, calcium stearate, modified nano barium sulfate, organic silicon resin, nano calcium carbonate and aids. Compared with the conventional waterproof coating, the vapor permeation-resistant coating disclosed by the invention has the advantages of being hard in film, excellent in wear resistance and high in adhesive force and particularly suitable for usage of the chemical pump, and has excellent water resistance. The modified nano barium sulfate is added into the ingredients, and due to the synergistic effect of the modified nano barium sulfate and the aids prepared in the invention, the adhesive force, high-temperature resistance, low-temperature resistance and ductility of the coating are greatly improved, and the vapor permeation resistance of the coating is improved, so that damage of vapor permeation on the coating is avoided, and multiple excellent performances are integrated.