Abstract: In order to assess the control effects of symbiotic bacteria of different species entomopathogenic nematode (EPN) on Meloidogyne spp. as well as the metabolites of those symbiotic bacteria on egg hatching and larval activity of root-knot nematodes, we conducted a pot experiment with quantitative inoculation in greenhouse and a bioassay test in laboratory. The results showed that symbiotic bacteria of entomopathogenic nematode Xb-IGA and Pl-IGA exhibited good suppressive effect on the reproduction of M. incognita eggs, and the inhibition rate ranged 59.4% ~ 73.9% when M. incognita was inoculated with 1 000, 2 000 and 5 000 eggs·plant⁻¹ on Zhongshu 4 tomato. When M. hapla was inoculated with 2 000 eggs·plant⁻¹ on VFNT tomato, the inhibition rate of EPN symbiotic bacteria Pl-IGA reached the maximum value of 74.5%, which was not significantly different from the conventional control, i.e avermectin (82.2%). Symbiotic bacteria of four species EPN effectively reduced the incidence of M. hapla and M. incognita infection, also promoted the root growth of tomato. After 7 days of bioassay, the 2× and 5× dilutions of metabolites by four species of symbiotic bacteria exhibited significant inhibition on the egg hatching of M. incognita and M. hapla. The corrected mortality of M. incognita larvae was 34.2% ~ 47.8%, and that of M. hapla was 59.6% ~ 79.9%. Therefore, symbiotic bacteria of entomopathogenic nematode and their metabolites showed great potential as biological nematicide resources for controlling root-knot nematode.