Intestinal mucositis causes great suffering to cancer patients who undergo chemotherapy and radiotherapy. Owing to the uncertain side effects of anticancer drugs to attenuate patients’ intestinal mucositis, many studies focused on traditional Chinese medicine (TCM). Patchouli alcohol (PA) is an active compound extracted from Pogostemon cablin, and has potent gastrointestinal protective effect. However, whether PA has an effect on intestinal mucositis is still unknown. Therefore, we established a rat model of intestinal mucositis via intraperitoneal injection of 5-fluorouracil, and intragastrically administrated PA (10, 20, and 40 mg/kg) to evaluate the effect of PA on intestinal mucositis. The routine observation (body weight, food intake, and diarrhea) in rats was used to detect whether PA had an effect on intestinal mucositis. Levels of inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-10, and MPO), mucosal barrier proteins (zonula occludens -1 (ZO-1), claudin-1, occludin, myosin light chain (MLC), and mucin-2) and intestinal microbiota were determined to elucidate the underlying mechanism of PA action on intestinal mucositis in rats. The results showed that PA could effectively improve body weight, food intake, and diarrhea in intestinal mucositis rats, preliminary confirming PA efficacy. Further experiments revealed that PA not only decreased the levels of TNF-α, IL-1β, IL-6, and MPO but also increased the level of IL-10 significantly. In addition, the expression of mucosal barrier proteins and microbiota community were also improved after PA treatment in diseased rats. Hence, PA may prevent the development and progression of intestinal mucositis by improving inflammation, protecting mucosal barrier, and regulating intestinal microbiota.