The invention discloses an antibacterial mildew-resistant interior environment-friendly coating capable of removing methanal with high efficiency, and a preparation method thereof. The antibacterial mildew-resistant interior environment-friendly coating is prepared from, by weight, 40 to 52 parts of a film forming base material, 10 to 22 parts of calcium carbonate powder, 16 to 28 parts of bamboo charcoal powder, 6 to 12 parts of talcum powder, 1 to 7 parts of a wetting agent, 1 to 7 parts of an antifoaming agent, 6 to 12 parts of a thickening agent, and 2 to 6 parts of a traditional Chinese medicine composition extracted solution; the traditional Chinese medicine composition extracted solution is prepared from, by weight, 10 to 16 parts of passiflora edulia sims, 8 to 14 parts of lemon, 4 to 10 parts of spina gleditsiae, 2 to 8 parts of acorus calamus, 12 to 18 parts of semen cassiae, and 2 to 8 parts of mint. The traditional Chinese medicine composition extracted solution possesses obvious inhibiting and killing effect on pathogenic bacteria and virus, no bacteria drug resistance is caused, and bacteria killing effect lasts long; the traditional Chinese medicine composition extracted solution and the chemical ingredients are combined, so that application of chemically synthesized additives is reduced, coating toxicity is reduced, methanal in the air can be removed effectively, safety is high, air purifying effect is achieved, fragrance is provided, and market prospect is promising.