Abstract: The fungicidal activities of extracts and fractions from Xenorhabdus nematophilus,code named YL001 cells were tested in vitro and in vivo.The bioassay results indicated that fungicidal activity of ethanol extract and methanol extract was higher than that of other extracts. The ethanol extract was subjected to chromatography silica gel(200~300 mesh)using CHCl3 -methanol with increasing amounts of methanol. The resulting 8 fractions with different hydrophobicities were analyzed by in vitro antibacterial activity assay to Botrytis cinerea. The result showed that fraction 6 was more active than others and the inhibition rate against the mycelial growth of Botrytis cinerea was 96.09% after 96 hours. The result also indicated that fungicidal components were mainly in fraction 6,fraction 7 and fraction 8. In addition,protective effect and therapeutic effect of the cells products at 10 mg/mL against the Botrytis cinerea were 64.81% and 62.03% on tomato,respectively.