The invention discloses a plant active easy-to-decompose environmentally-friendly mosquito-repellent enzyme and a preparation method thereof, and the plant active easy-to-decompose environmentally-friendly mosquito-repellent enzyme comprises two parts, one part comprises daphne odera essential oil, allicin, chamomile essential oil, methyl chavicol, limonene, caryophyllene, volatile oil of artemisia argyi leaves, flavonoids of artemisia argyi leaves, amino acids, vitamins and other invalid organic compounds which are obtained by obtaining from Common jasmin orange leaves, washed waste citrus peel, fresh garlic flakes, Agastache rugosus leaves, clove leaves and artemisia argyi leaves by use of the vital action of a Thermomonospora curvata microbial inoculum, a corn smut microbial inoculum and an aerobic sliding slime mold microbial inoculum, extracting with water, ethanol and ethyl acetate, and applying with a strong magnetic field. The other part is mixed nutrient powder composed of bean cake powder and corn starch, and wood candida mycoderma bacteria is also cultivated in the nutrient powder. The plant active easy-to-decompose environmentally-friendly mosquito-repellent enzyme haswide sources, low cost, detailed and easy manufacturing process, quick effect, long-lasting effect, environmental protection, no pollution and easy decomposition.