This experiment was conducted to evaluate the predacity efficiency for some nematode-trapping fungi and determine their mechanism of effects on root-knot nematode Meloidogyne javanica. The results showed the differences between the tested species Arthrobotrys oligospora Fres., A. conoides Drechsler, A. arthrobotryoides (Berlese) Lindau, A.cladodes Drechsler, Nematoctonus haptocladus Drechsler, N. robustus Jones, Dactylaria candida (Nees:Fr.) Schenck, Kendrick&Pramer, Dactylella brochopaga Drechsler, D. lepyosporo, Monacrosporium eudermatum. Monacrosporium sp. In the predacity efficiency after 9 and 18days of inoculation, the number of killed nematode in the treatments of all fungi ranged 30.0-99.33 and 36.66-100.00 nematode after 9 and 18 days respectively. A. oligospora was Significantly superior than the rest other fungi, but it wasn't significantly differ from D.brochopaga. while A. cladodes showed lower predacity efficiency. In the effect of fungal colony age in the predacity efficiency. the results revealed that the 18days colony age gave significantly higher predacity efficiency from 9days colony age and the fungus 4. oligospora gave the highest predacity efficiency after 18days, the number of killed nematode in its treatment 100. followed by the fungus D. brochopaga with 98.66 mean number of killed nematode, while the fungus A. cladodes in the age of 9 days showed less predacity efficiency with 30 mean number of killed nematode in its treatment. The results showed that the pure filtrate of A. oligospora doesn't affect the root-knot nematode, while the extract of the infected root-knot nematode with five isolates of A. oligospora individually revealed significantly higher number of killed nematode after 12 and 24h of inoculation, the number of killed nematode in the treatments of the five isolates ranged 95.00-96.66 and 100.00nematode for the two periods respectively, compared with 2.33 and 2.66 number of killed nematode in the control treatment for the two periods respectively. Results of evaluations of five materials (nematode suspension, distill water, 2%ethanol alcohol, 0.1 sodium hydroxide and water agar) in the induction of trapping devices in the fungus A. oligospora also showed that all the materials induced formation of the traps, and the nematode suspension was the most efficient between them.