The so called normal intestinal microflora is the bacteria in intestine. The quality of the lab animals has much related to the profiles of the normal intestinal microflora. The balance of the intestinal microflora shows very strong and important effect on keeping the normal functions of the animals. In mice's intestine,there are nearly 100 million bacteria per gram dejection, which belong to almost 100 strains. The sorts of the bacteria are varied in different strains' mice.The researches about normal intestinal microflora of mice are reviewed in this article.