The species ,distribution and harm of weeds of buckwheat fields in Liangshan, were investigated, the results show that according to incomplete statistics, buckwheat weeds in wheat field in Liangshan, , there are 22 families 59 species. Dicotyledonous weeds Galinsoga parviflora, Polygonum lapathifolium , Amaranthus blitum, Nepal, Bidens pilosa, Shepherd's purse, Chickweed, Chenopodium album and Monocotyledonous weeds Barnyardgrass, Commelina communis are the dominant population of buckwheat field in Liangshan.