The invention relates to the technical field of mosquito repelling and insect preventing sachets and specifically relates to a mosquito repelling and insect preventing sachet which is prepared from the following ingredients: rhizoma nerdostachyos, rhizoma kaempferiae, herba lysimachiae foenum-graeci, borneol, camphor, rhizoma acori graminei, Chinese mugwort herb, herba asari and semen zanthoxyli.The invention further discloses a preparation method of the sachet. The preparation method comprises the steps of treating all the ingredients; then mixing and stir frying the treated rhizoma nerdostachyos, the treated rhizoma kaempferiae, the treated herba lysimachiae foenum-graeci and the treated herba asari, cooling and mixing with the borneol, the camphor, the rhizoma acori graminei, the Chinese mugwort herb and the semen zanthoxyli; smashing, sieving and filling into a sachet bag to obtain the sachet. The sachet disclosed by the invention has the advantages of pleasant fragrance, high user acceptability, more obvious insect preventing effect and no toxic and side effect. The sachet can prevent insect and mould. The rhizoma nerdostachyos in the sachet has the advantages of light flavor, durability and thickness, so that the rhizoma nerdostachyos can make flavor of all the herbs be released slowly for a long time.