Seven bacterial strains with strong antagonistic effect on the pathogen of cucumber Fusarium oxysporum were isolated from the rhizosphere soil,root and stem of cucumber,and the inhibition rate of these bacteria on the plate was up to 46%. Four strains including GJ-9,NH-1,P7 and XX2J7 with resistance to rifampicin were obtained. The results showed that these strains had good colonization ability in the cucumber seedling and could be transported into the stem through the root,which could significantly improve the activity of defense-related enzyme such as PAL,POD and PPO in the cucumber seedlings. The results showed that the fermentation broth of the antagonistic bacteria NH-1 had significant effect on the control of the cucumber Fusarium wilt,the disease index of the treated cucumber seedlings was 26.00,and its control effect reached 66.03%. According to the growth morphological characteristics and its gyrb gene sequence analysis,this bacteria was identified as Bacillus velezensis.