Abstract:[Objective] To investigate the effect of thymol and carvacrol on diarrhea, short-chain fatty acids (SCFA), and microbial composition of Tan lambs, thus to provide plant extracts-derived additives for the treatment of lamb diarrhea, and lay a theoretical basis for the treatment. [Methods] A total of ten diarrhea lambs (diarrhea had lasted 2-3 days) were randomized into diarrhea group (CON) and thymol and carvacrol group (SCAT). The lambs in the SCAT group were supplemented with a mixture of thymol and carvacrol (1:1) at 200 mg/d for 7 days. [Results] Thymol and carvacrol improved the daily weight grain, decreased the diarrhea index, diarrhea rate (P<0.05), and concentration of serum pro-inflammatory factors (P<0.05), and increased the concentration of intestinal butyric acid (P<0.05) of the diarrhea lambs. Thymol and carvonol also changed the gut microbial composition of diarrhea lambs, raised the relative abundance of Bifidobacteriaceae and Akkermansiaceae, and decreased the relative abundance of Enterobacteriaceae.[Conclusion] Thymol and carvonol can improve the relative abundance of gut probiotics and butyric acid concentration and reduce the relative abundance of pathogenic bacteria, therefore, it can effectively inhibit lamb diarrhea, and can be used as a new type of anti-antibody product for research and development.