In order to research the effect of Bacillus cereus on the growth rate and intestinal microflora of Litopenaeus vannamei, Bacillus cereus (number PC465) was added to basic feed with concentration of viable bacteria of 10⁸ CFU/g. Shrimps living in 8 pools with the similar light and position were divided into two groups, and the experimental group was fed the immune feed everyday while the blank control group were fed basic feed. Shrimps were fed with a complete breeding cycle (95days) in the farm. Sampled at Day 45, 52, 59, 66, 73, the method of high throughput sequencing of 16S rDNA gene's V4 region was used to determine diversity and composition of bacterial communities in each of these samples. Experiment showed: (1) The growth rate of the experimental group was average 15.2% higher than the blank control group. (2) The intestinal microflora of L.vannamei contained high proportion of Proteobacteria and Bacteroidetes, while Firmicutes, Verrucomicrobia, Planctomycetes, Actinobacteria were at lower rate. (3) In intestinal microflora of the blank control group' shrimps, the average proportion of Proteobacteria (68.30%) was higher than the experimental group (57.94%), while Bacteroidetes was lower than the control group. Proteobacteria was mainly composed of Vibrio, Anaerospora and Rhodovulum. The blank control group' average proportion of Vibrio was 5.40%, while the experimental group was 1.94%. Bacteroidete was mainly of Lutimonas and Tenacibaculum. The blank control group' average proportion of Lutimonas was 5.56%, while the experimental group was 8.12%. The results of the study suggest that dietary with Bacillus cereus can change the intestinal microflora of L. vannamei and enhance its growth.