Abstract: The microfloral change was explored by PCR- denaturing gradient gel eletrophoresis( PCR- DGGE) and p H,TVB- N,the total number of colonies were measured every three days in vacuum- packaged beef at 4 ℃.Results showed that,vacuum- packaged beef storaged at 4 ℃,the total number of colonies during the twelfth days of storage had more than 6.0 lg cfu / g,p H during the twenty- first days of storage more than 6.0,TVB- N during the eighteenth days of storage more than 25 mg /100 g,according to physical and chemical indicators showed that vacuum packaged chilled beef storage period for 12 days. Ochrobactrum sp.,Bosea vestrisii,Macrococcus caseolyticus predominated in early stage during chilled storage,whereas in the end of storage period Pantoea agglomerans,Brochothrix thermosphacta,Carnobacterium divergens,Bradyrhizobiaceae,Lactobacillus sp.,Ewingella Americana,Rahnella aquatilis,Enterobacteriaceae predominated.