Abstract: Banana fusarium wilt was an important soil-borne disease in the production of banana. Biological control was one of the effective ways to prevent the occurrence of this disease. A group of composite microbial agent (Bacillus amyloliquefaciens NJ-1 and Trchoderma T05-49) was obtained by using the methods of plate growth co-culture of different microbial agents and the antimicrobial activation measurement of fermentation broth. The effects of compound microbial agent (NJ-1+T05-49) on the prevention efficacy of banana fusarium wilt, the growth-promoting effect of banana and the number of microbial population in rhizosphere soil were measured by using the method of irrigating the root with fermentation broth. The results showed that the prevention efficacy of the fermentation broth of composite microbial agent, Bacillus amyloliquefaciens NJ-1 and Trchoderma T05-49 on banana fusarium wilt were 78.92%, 66.46% and 52.46%, respectively. Compared with the fermentation broth of Bacillus amyloliquefaciens NJ-1 and Trchoderma T05-49, the prevention efficacy of composite microbial agent on the disease was increased by 18.75% and 50.43%, respectively. The plant height and main root length were increased by 9.22%, 26.87% and 8.58%, 21.95%, respectively. After being treated with the compound microbial agent for 21 days, the number of bacteria and actinomycetes in the rhizosphere soil were 9.10×10⁶ cfu·g⁻¹ and 20.83×10⁵ cfu·g⁻¹, respectively, and the number of fungi was 0.70×10³ cfu·g⁻¹. The number of bacteria and actinomycetes was significantly increased. The results provided the basis for the development and application of composite microbial agent（NJ-1+T05-49）in the biological control of banana fusarium wilt.