Abstract: The allelopathy of the extracts of the above-grould and under-ground parts of Dicranopteris pedata on several weeds and crops was studied. The results showed that (1) The extracts inhibited the germnation of all the weeds, radish and Chinese cabbage, and the root growth of all the seedlings and the shoot height of majority of the seedlings; (2) the etract from the above-ground part had stronger allelopathic effect than that from the under-ground part; (3) the extract inhibit the growth of the root more strongly than the stem and foliage.