The antibacterial component was extracted from vaccinium bracteatum thunb leaves and its antibacterial effect was studied. Choosing ethanol as extraction solvent, the optimum extraction conditions were determined by single factor experiment and orthogonal experiment, which was 85% ethanol concentration, temperature 90 ℃, solid-liquid ratio 1∶16, time 4 h. The inhibiting effect was determined by oxford cup method. The average inhibition zones against escherichia coli, staphylococcus aureus, yeast, mucor and aspergillus were 18 mm, 16 mm, 13 mm, 15 mm and 14 mm, respectively. The content of flavonoid, which was the main bacteriostasis component, was 39.5 mg/g determined by spectrophotometry. The fresh-keeping effect of the extract on flour products was studied. After heat preservation experiment, the flour products with the extract excelled control group in the indexes, such as total number of bacterial colony, acidity, and pathogenic microorganism, which indicated that the leaves possess good fresh-keeping effect.