Abstract: Agar diffusion method was used to investigate the inhibiting effect of Staphylococcus aureus,Escherichia coli and Bacillus subtilis by different polar fractions inculding chloroform fraction,ethyl acetate fraction,n- butyl alcohol fraction and water layer fraction from the Qingzhuan brick tea extract,and their minimum bacteriostatic concentration and total polyphenol content were determined. The results showed that the antimicrobial activity of ethyl acetate fraction among different polar fractions was the best and the antimicrobial diameters on inhibiting Staphylococcus aureus,Escherichia coliand Bacillus subtilisare were respectively 29.19,27.97,27.35 mm when its concentration was 100 mg / m L.The minimum inhibitory concentrations for Staphylococcus aureus,Escherichia coli and Bacillus subtilis were,3.12,6.25 mg / m L,respectively.The total polyphenol content in ethyl acetate fraction was as high as 81.62% and the total polyphenol may be the main active ingredients on its bacteriostasis.