Abstract: 【Objective】 The aim of this project is to study the effects oflactobacillus rhamnoides on the diversity and species abundance in feces of mice during pregnancy. 【Methods】 The test selected 30 Kunming pregnant mice with similar weight (23.33±1.55) g, and with the same mating date and they were randomly divided into 2 groups, 15 in each group, respectively, the control group and the test group. Under the same feeding conditions and dietary nutrition level, the control group was fed with the basic diet without any treatment. The mice in the test group were fed with 0.5 mL sterilized saline containing 0.125 g Lactobacillus rhamnoides on the basis of feeding the basic diet, and the test period lasted 21 days. 【Results】 The results showed that :(1) Lactobacillus rhamnoides had no significant effect on the diversity of fecal flora in mice (P>0.05), but decreased the Simpson index in the experimental group. (2) At the phylum level, the amount of abundance of Firmicutes, Bacteroidetes and Proteobacteria was above 90%, and the Firmicutes was significantly higher than that of the control group (P<0.05), but the Bacteroidetes and Proteobacteria were 21.95%(P<0.05) and 26.15% (P<0.05) lower than those of the control group. At the family level, the test groups of the Lachnospiraceae, Lactobacillaceae and Erysipelotrichaceae were significantly higher than those of the control group (P<0.05). On the genus level, the Lactobacillus, the genus of unide.pngied_Lachnospiraceae and the Lachnoclostridium test group were significantly higher than those of the control group (P<0.05). 【Conclusion】 From this, we can see that under the conditions of this experiment, the feeding of Lactobacillus rhamnoides in pregnant mice has no significant effect on the diversity of fecal flora, but it can improve the species abundance of intestinal bacteria in mice, and produces significant effect on the abundance of Firmicutes, Lachnospiraceae, Lactobacillaceae, Erysipelotrichaceae, Lactobacillus, unide.pngied_Lachnospiraceae and Lachnoclostridium.