The invention discloses the use of a compound dehydrorhizotoxin, which is isolated and extracted from secondary metabolites of Curvularia sp., including the steps of fermentation of strains, extraction of secondary metabolites and separation and purification Complete, the purposes of the compound dehydroradicin in the preparation of herbicides, the compound dehydroradicin (Dehydroradicin) obtained by the present invention as a herbicide, in use, that is, when the concentration is 100 μg / mL, to Five common wild weeds that are difficult to eradicate with general herbicides, Amaranthus retroflexus, alfalfa, bluegrass, barnyardgrass, and the invasive plant Cocklebur sativa significantly inhibit the growth of seedlings, and they are prepared at different concentrations at the same time. Mixed with other pesticides, it is widely used in the development of various herbicides, and has great potential commercial application value.