The invention discloses a formula and a preparation method of a multifunctional damp-proof coating, which relate to the technical field of air purification and air humidity reduction. The coating comprises the following components by weight: 20%-30% of 310TS emulsion, 5%-15% of silica solution, 10%-20% of water, 10%-20% of diatomite filter aid, 10%-20% of wollastonite acicular powder, 5%-10% of light calcium carbonate, 5%-10% of zeolite, 0.8%-1% of negative ion element, 0.5%-2.5% of wetting agent 188A, 0.5%-2.5% of levelling agent 2020, 0.5%-2.5% of coalescing agent alcohol ester-12, 0.5%-1.5% of anti-freezing agent ethylene glycol, 0.5%-2.5% of thickener 935, 0.1%-0.5% of defoamer NXZ, 0.1%-1.0% of dispersing agent 8045, and 0.2%-0.8% of mildew preventative. The preparation method of the coating comprises the process of: uniformly mixing a solid material and a liquid material according to the proportion of 10:7.5; adding the mixed materials into a mixer; mixing and kneading the materials for 30 minutes at a low temperature; and finishing mixing till the coating is greasy. With the formula and the preparation method of the multifunctional damp-proof coating disclosed by the invention, the energy is saved, the environment is protected, energy consumption is reduced, and low-carbon emission reduction is realized; the coating can well absorb condensation water so as to reduce air humidity, and can also absorb harmful gas such as benzene; and the product is unique, the formula is novel, and the coating is suitable for buildings and power equipment, etc.