Abstract: In order to study the effects of amino acids on the nematode-trapping organs forming of Arthrobotrys oligospora, 0.5 mL solutions of amino acids（0.5, 0.05 and 0.005 g·L^-1）were spreaded over the CMA with A. oligospora in different growing stages respectively, then they were incubated in 25 ℃. The results showed that different amino acids had different effects on the traps forming. Among all of the amino acids tested, L-Phenylalanine, L-Methionine and DL-Valine of 0.05 g·L^-1 solutions had the best effects on inducing traps, and L-Threonine, DL-Phenylalanine, L-Isoleucine, L-Tryptophanea, DL-Leucine, L-Leucine and L-valine had better effects than the others, but worse than the former ones. It was easier for young hyphae to produce traps, which were similar in trapping and killing nematodes with those induced by nematode larvae, than the older ones when they were induced by amino acids. All those showed that the nematode-trapping organs of A.oligospora could induce not only by nematodes but also by amino acids, and they could also trap and kill larvae of nematodes effectively, which was very useful and important to study the biochemical mechanism of nematode-trapping fungi.