Abstract: Lactobacillus plantarum were natural components of the normal intestinal microbiota in both humans and animals, and it could be isolated from fermented meat or milk. Rats were randomly assigned into four treatments feeding of Lactobacillus plantarum X3-2B, to evaluate the effects of suplenentation of Lactobacillus plantarum with different dosage on microbial flora in rat's gut. The results indicated that different dosage increased consumption index ( CI) of rats and decreased p H of feces ( Minimum high dose group) , viable counts of Lactic acid bacteria and Bifidobacterium of experimental group were significantly higher (p <0.05) than negative control group. Enterobacteriaceae, Enterococcus of experimental group were lower after fed X3-2B for 14 days compared with fed for 1 day (p<0.05) , and Lactobacillus plantarum X3-2Bcould resist the growth of harmful bacteria and adjustment role of the intestinal microflora.