Abstract: Two strains of Fusarium spp., VL-1 and VL-2, were isolated from inside of cotton bolls. The result of pair culture showed that the two strains of fungi grew very fast and inhibited the growth of Verticillium dahliae through nutrition and space competition. In addition, they also inhibited the production of microsclerotia of V. dahliae. The relative control effects of VL-1 and VL-2 against cotton Verticillium wilt were 87.9% and 66.4% respectively under greenhouse condition. The safety test showed that VL-1 and VL-2 were avirulent strains of Fusarium spp. The results of field test indicated that the relative control effects of VL-1 and VL-2 were 51.5% and 45.4% respectively during the first disease incidence peak of cotton Verticillium wilt.