Abstract: The clinical capacity of the nematode-trapping fungus——Arthrobotrys oligospora to kill parasitic nematodes of livestock was studied. The experiment indicated that the killing rate was 96.3% (sheep), 96.5% (cattle), 97.4% (horse) respectively after feeding the conidia to animals, which showed that the fungus could pass through the digestive canal of animals and have preserved its trapping capacity. The result established an important foundation for the clinical application of nematode-trapping fungi.