Abstract: 344 actinomycete isolates were gained from 30 soil samples in Nanjing, Huaiying, Shanghai. Their antagonism against Meloidogyne incognita was tested in vitro and in greenhouse. Culture filtrate of one strain (LH121) could knock-down 100% of the J2 individuals of M. incognita within 4h and killed 100% within 12h. In greenhouse experiments, 2ml culture filtrate per tomato plant could inhibit 52.8% gall formation and 63.5% egg mass formation. LH121 could produce nematicidal compounds stably after continuously transferation. Further study showed that LH121 was mainly through directly killing J2 or disturbing infection process to control nematodes population, it had no effect on development of the nematode within host plant. LH121 was identified as Streptomyces reseofulvus based on its morphology, culture characters as well as physiological and biochemical characteristics.