Abstract: The biological control effect of a strain of Bacillus velezensis B18 on Fusarium oxysporum f. sp.cubense race 4（Foc TR4） was mainly studied in this study. During the analysis and screening of cassava rhizosphere soil microorganisms, an antagonistic bacterium B18 that inhibits the growth of Foc TR4 was found. B18 was identified by combining cell morphology judgment, biochemical physical and chemical testing and molecular biology analysis of 16SrDNA and gyrB genes. The plate confrontation method was used to explore the antagonistic effects of B18 bacterial suspension and fermentation supernatant on Foc TR4. In the greenhouse potted conditions, the banana seedlings were irrigated with B18 bacterial suspension to explore its control effect on banana wilt caused by Foc TR4. The results showed that the bacterial suspension of B18 could effectively inhibit the mycelial growth of Foc TR4. Further pot experiment found that B18 showed obvious resistance to banana wilt caused by Foc TR4. The control effect was as high as 67.9%. The research results show that B18 has certain application potential and value in the control of banana Fusarium wilt which can be used as a biocontrol agent for the control of banana fusarium wilt.