Abstract: In order to effectively prevent and control the disease caused by common tobacco mosaic virus (TMV), a bacterium strain, Z5, resistant to TMV was isolated from soil and was identified as Bacillus velezensis through morphological, physiological, biochemical and molecular biological tests. The culture solution of this bacterium had an in vitro inhibition rate against TMV up to 96.40% and a control effect of 50.43% on TMV in field plot experiments. After the optimization of fermentation condition through a single factor experiment, the optimal medium for strain Z5 was NB medium with glucose and yeast extract as carbon and nitrogen sources respectively, and the optimum conditions were initial pH 7.0, medium volume 100 mL/250mL and fermentation at 28 ℃ for 60-72 h. Under the optimized condition, the bacterial count increased by 44.38% and the fermentation broth had a stable inhibitory effect against TMV with an inhibition rate of 98.71%.