Abstract: Strain QD-10 isolated from mud in Yellow Sea near Qingdao, Shandong Province, showed highly antagonistic activities in inhibiting fungi and bacteria. It was identified as Bacillus amyloliquefaciens based on morphological, physiological and biochemical characteristics. The strain had a broad antimicrobial spectrum according to the tests on 14 plant pathogenic fungi, and 2 pathogenic bacteria. The strain was capable of producing siderophore, protease, cellulase and IAA. Treatment of tomato fruits with the fermentation broth of the strain at original and 5 times diluted solution could reduce gray mold by 100% and 41.7% at the 11th day after inoculation, respectively, higher than that of treatments with polyoxin and carbendazim.