Abstract: 【Objective】Bacillus amyloliquefaciens HZM9 is a plant growth-promoting rhizobacterium with potent biocontrol activity, and its inhibitory spectrum and stability were studied to develop this strain as a bioagent to suppress soil-borne plant diseases. 【Method】The growth rate of 10 soil-borne plant pathogens was measured to test the inhibitory spectrum of the HZM9 culture filtrate. In addition, the growth rate of Fusarium oxysporum was tested to determine the stability of the HZM9 culture filtrate. 【Result】The results showed that the filtrate exhibited a broad spectrum against all 10 soil borne plant pathogens. In particular, Sclerotinia sclerotiorum and Fusarium oxysporum were strongly inhibited by the filtrate with an inhibitory rate of 90%. Antibacterial activity of the HZM9 filtrate had good thermal stability. When the temperature was higher than 80 ℃, the inhibitory rate of the strain HZM9 almost unchanged, and remained higher than 80%. At the temperature of 100 ℃ treated for 30 min, the inhibitory rate decreased to 66.55%, and for 30 min at 100 ℃, the inhibitory rate could still reach 58.78%.It was stable when exposed to a dose of light and ultraviolet rays. It was also stable at pH 5-9 and after proteases treatment. The filtrate could be stored with stable activity at 4 ℃ for 150 d.【Conclusion】 B. amyloliquefaciens HZM9 culture filtrate has a broad inhibitory spectrum and good stability, therefore, it could potentially be used in the biological control of soil-borne plant diseases.