Efficiency of different concentrations of Trichoderma longibrachiatum T6 against Meloidogyne incognita and its rhizosphere colonization in cucumber were determined in greenhouse experiments. The results of rhizosphere colonization experiments showed that the number of colonies in cucumber soil and root increased significantly ten weeks after inoculation with the second stage juveniles of M. incognita and different concentrations of T. longibrachiatum T6, and there was significant difference in different concentrations of T. longibrachiatum T6, e.g., the maximum numbers of colonies in soil and root were 7.8 x 10⁷ and 6.3 x 10⁵ CFU · mL⁻¹ respectively after treated with the spore suspension of 1.5 x 10⁷ CFU · mL⁻¹. Greenhouse experiments results showed that different concentrations of T. longibrachiatum T6 had significant control effect on different life stages of M. incognita, and the control effect increased with the concentration of T. longibrachiatum T6. T. longibrachiatum T6 significantly increased plant height, root length, above-ground and root fresh mass o cucumber inoculated by M. incognita. T. longibrachiatum T6 could colonize in cucumber rhizosphere, had control effect on M. incognita, and significantly improved the growth of cucumber.