The invention discloses an environmentally friendly insect repellant formula for preventing agricultural pollution and a preparation method thereof. The environmentally friendly insect repellant formula is prepared from the following components in parts by weight: 100-200 parts of water, 5-9 parts of imidacloprid, 5-13 parts of lavender extract, 6-13 parts of Chinese chive extract, 6-14 parts of cosmos extract, 5-13 parts of lemon balm extract, 4-10 parts of catnip extract, 6-15 parts of chamomile extract, 6-10 parts of Chinese mugwort extract, 10-15 parts of buttonwood bark extract, 7-16 parts of evening primrose extract, 5-13 parts of geranium extract, 4-7 parts of marigold extract, 4-10 parts of citronella extract, 2-8 parts of fructus anisi stellati extract, 4-12 parts of michelia albaextract, 4-14 parts of oregano extract, 6-15 parts of perilla frutescens extract, 6-15 parts of folium artemisiae argyi extract, 6-15 parts of radix dichroa extract, 6-16 parts of rohdea japonica extract, 4-9 parts of rosemary extract, 13-16 parts of chilli extract, 4-9 parts of borage extract and 3- 9 parts of tropaeolum majus extract.