This study investigated the appropriate way of dietary Acer truncatumleaves (ATL) addition, the effect of disease prevention and its mechanism of action. In experiment 1, 192 Arbor Acres broilers were assigned to 4 treatment groups, fed with basal diets containing 2% bran, replacing it with primary and fermented ATL, and additional 0.3% ATL extract to the basal diet for 42 d, respectively. In experiment 2, 144 broilers were assigned to 3 treatment groups for 21-d trial: (1) C-N group, basal diets, and injected with 0.9% (w/v) sterile saline; (2) C-L group, basal diets, and injected with lipopolysaccharide (LPS); (3) T-L group, ATL diets and injected with LPS. In experiment 1, ATL significantly decreased the index of abdominal fat at 42 d (P< 0.05). ATL extract had a better ability to improve antioxidant capacity and reduce inflammatory levels among all treatment groups, which significantly decreased the content of MDA in the liver and ileum mucosa at 21 d, and increased the expression of IL-10and Occludinin jejunal mucosa at 42 d (P< 0.05). In experiment 2, ATL significantly increased the level of T-AOC in the liver, decreased the expression of NF-κBin the jejunal mucosa and ileum mucosa (P< 0.05), and restored LPS-induced the changed level of CAT in jejunal mucosa, the expression of IL-6, Claudin-1, and ZO-1in jejunal mucosa and IL-1βin ileum mucosa (P< 0.05). Analysis of gut microbiota indicated that ATL enhanced the abundances of Bacteroidotaand reduced the proportion of Firmicutes(P< 0.05), and the changed levels of T-AOC in body, IL-1β, IL-6, IL-10, and NF-κBin jejunum mucosa and propionic acid in cecal were associated with gut microbiota. Collectively, our data showed that the extract of ATL had a better antioxidant and anti-inflammatory effects than primality and fermented. Extraction of ATL modulated intestinal microbiota, and had a protective effect on oxidative stress, inflammation, and intestinal barrier function in broilers challenged with LPS.