Abstract: The effect of a Bacillus commercial probiotic on intestinal microflora of white shrimp Litopenaeus vannamei was investigated by Biolog-ECO and nutrition agar at the late farming stage, comparing the shrimps farmed in ponds utilized bacillus commercial probiotic with the control ones farmed in tanks utilized nothing. Gram-negative bacteria were the dominant culturable bacteria of shrimp intestinal microflora of two ponds. In the pond used the probiotic, the total counts of culturable bacteria were lower than that in control pond, while the Shannon index, Simpson index, McIntosh index and the function of carbon utilization of shrimp intestinal microflora increased significantly(P0.05). The results indicate that Bacillus commerial probiotic can improve the function of carbon utilization of shrimp intestinal microflora.