Abstract: Egg-parasitic fungi have been investigated as a potentially useful biological control agent against root-knot nematodes. In these study, the parasitism of tobacco root-knot nematode eggs, female and the inhibition in hatch of egg masses were measured in vitro, and the biocontrol potential on the tobacco root-knot nematodes in the field were evaluated by Lecanicillium psalliotae CGMCC5329. The fungus colonized the root-knot nematodes eggs, females, and demonstrated the great suppression in hatch of egg masses. The egg parasiting rate by the fungus was 83.29% on the 5th day; the inhibition in hatch of egg masses was 91.41% on the 15th day. The relative effect control of tobacco root-knot nematodes was over 80% in the field with the fungal agent applying volume of 15 kg/667m². This study suggests that L. psalliotae CGMCC5329 has great potential use for biological control against root knot nematodes.