In this paper, 160 three-way cross lean diarrhea pigs of 7-15-day-old have been selected to carry out the test to evaluate the results of Bacillus Subtilis therapy instead of antibiotics. The groups have been divided into the control group and test group, and in the same feeding and management conditions, pigs in the control group have been fed with antibiotics, pigs in the test group with Bacillus Subtilis. 5 to 7 days later, the results of the two therapies have been compared. The results show that Bacillus Subtilis can not only replace antibiotics to treat piglet diarrhea, but also avoid the drugs＇ damage on the pig organ in real terms and not affect the production performance of pigs.