Plant growth-promoting rhizobacteria （PGPR） are considered to be the most promising agents for cash crop production via increasing crop yields and decreasing disease occurrence. The Bacillus amyloliquefaciens strain W19 can produce secondary metabolites （iturin and bacillomycin D） effectively against Fusarium oxysporum f. sp. cubense （FOC）. In this study, the ability of a bio-organic fertilizer （BIO） containing strain W19 to promote plant growth and suppress the Fusarium wilt of banana was evaluated in both pot and field experiments. The results showed that application of BIO significantly promoted the growth and fruit yield of banana while suppressing the banana Fusariurn wilt disease. To further determine the beneficial mechanisms of the strain, the colonization of green fluorescent protein-tagged strain W19 on banana roots was observed using confocal laser scanning microscopy and scanning electron microscopy. The effect of banana root exudates on the formation of biofilm of strain W19 indicated that the banana root exudates may enhance colonization. In addition, the strain W19 was able to produce indole-3-acetic acid （IAA）, a plant growth-promoting hormone. The results of these experiments revealed that the application of strain W19-enriched BIO improved the banana root colonization of strain W19 and growth of banana and suppressed the Fusarium wilt. The PGPR strain W19 can be a useful biocontrol agent for the production of banana under field conditions.