Abstract: The antifungal activity of eugenol (a natural compound) against 10 fungal pathogens including Botrytis cinerea was detemined by mycelial growth rate method.The results showed the sensitivity of 7 strains of B.cinerea to eugenol was different, and the EC50 values were ranging from 29.97 to 83.62 μg/mL. Eugenol could reduce the sclerotium number,germination and sporulation,but had no effect on spores germination of B.cinerea.Hyphae of B.cinerea treated with eugenol showed strong propidium iodide fluorescence in the cytosol viewed with a fluorescence microscope.Eugenol could also increase the concentration of potassium ion and cellular materials in the medium.The results suggested that the cell membrane might be the target of eugenol.