This experiment was conducted to study the effects of dietary superfine grinding plantain on growth performance, immune function and antioxidant function of broilers with Salmonella infection. A total of 840 1-day-old male Cobb broilers were selected and divided into 10 treatments by using a randomized block design of 5 (superfine grinding plantain supplementation levels)×2 (Salmonella infection or not) two factors with 6 replicates for each treatment and 14 chickens for each replicate. The superfine grinding plantain in this experiment was a mixture of superfine grinding plantain grass and plantain seed with 1:1 mixing ratio. The supplemental levels of superfine grinding plantain were 0, 0.25%, 0.50%, 1.00% and 2.00% of the diet, respectively, by replacing the wheat bran in the basal diet. Each broiler in the infected group was orally infected with 1 mL freshly cultured Salmonella Typhimurium (CVCC 541, bacterial concentration was 1×10⁹ CFU/mL) at the age of 7 days, and that in the normal group was orally infected with the same amount of sterile nutrient broth at the age of 7 days. The experiment lasted for 42 days. The results showed as follows:1) dietary superfine grinding plantain had no significant effects on the growth performance of broilers from 1 to 7 days of age (P>0.05), and Salmonella infection significantly reduced the growth performance of broilers (P<0.05), but dietary superfine grinding plantain had no significant effects on the growth performance of broilers (P>0.05). 2) Compared with no superfine grinding plantain supplementation, dietary 0.50% superfine grinding plantain significantly increased the spleen index of broilers at 14 days of age in the infected group and at 42 days of age in the normal group (P<0.05), dietary 0.25% and 1.00% superfine grinding plantain significantly decreased the chyme secretory immunoglobulin A content in ileum of broilers in the infected group (P<0.05), dietary 2.00% superfine grinding plantain significantly increased the peripheral blood monocyte phagocytic activity of broilers at 21 and 42 days of age (P<0.05), dietary 0.50% superfine grinding plantain significantly increased the concanavalin A (ConA) stimulation index in peripheral blood lymphocytes of broilers at 21 days of age in the infected group (P<0.05), dietary 1.00% and 2.00% superfine grinding plantain significantly increased the ConA stimulation index in peripheral blood lymphocytes of broilers at 42 days of age (P<0.05), dietary 0.50% and 1.00% superfine grinding plantain significantly increased the lipopolysaccharide stimulation index in peripheral blood lymphocytes of broilers at 42 days of age (P<0.05). 3) Compared with no superfine grinding plantain supplementation, dietary 0.50% superfine grinding plantain significantly decreased the malondialdehyde (MDA) content in liver of broilers at 14 days of age (P<0.05), dietary 2.00% superfine grinding plantain significantly increased the activity of total superoxide dismutase and glutathion peroxidase in ileum of broilers at 21 days of age in the normal group (P<0.05), and dietary 0.50% superfine grinding plantain significantly decreased the intestinal heme oxygenase 1 gene expression of broilers in the infected group (P<0.05). 4) Compared with no superfine grinding plantain supplementation, dietary 1.00% superfine grinding plantain significantly increased the intestinal villus height of broilers at 14 and 21 days of age and intestinal mucosa thickness of broilers at 14 days of age (P<0.05). In conclusion, dietary superfine grinding plantain can improve the immune ability of broilers by promoting the development of spleen and the proliferation and differentiation of lymphocytes, increase the antioxidant capacity, protect the intestine morphology of broilers, and alleviate the negative effect of Salmonella infection on broilers to some extent.