To investigate the effects of Pithecellobium clypearia extract on the tissue structure,in-flammatory lesions as well as microbial diversity in the intestinal of yellow-feathered broilers.2401-day-old yellow-feathered broilers were randomly divided into four groups(groups A,B,C and D),groups A,B and C were supplemented with Pithecellobium clypearia extract in basal diets with concentrations of 0.5,1.0 and 2.0 g/kg,respectively.Group D served as the control group without adding Pithecellobium clypearia extract in diets,and the full trial period lasted for 70 d.Duodenum and jejunum samples were collected on the 20th,40th and 70th days of the test,the vil-lous/crypt ratio of duodenum and jejunum were calculated,and the mRNA expression level of in-flammatory cytokine as well as related pathways were detected in each group,respectively.In addition,the contents of cecum were collected at 70 th day of the experiment and the microbial di-versity in cecum were also analysed by 16S rDNA sequencing.The results showed that adding 0.5 and 1.0 g/kg of Pithecellobium clypearia extract in the diet could significantly increase the veloci-ty height/crypt depth ratio of duodenum and jejunum(P＜0.05)compared to control group,as well as the mRNA expression level of tight junction protein(CLDN1 and CLDN5)in jejunum,which further improved the structure of mucous of intestinal.Pithecellobium clypearia extract could significantly(P＜0.05)decrease the mRNA expression level of inflammatory cytokine inclu-ding IL-1β,IL-8 and TNF-α,as well as the related pathway genes such as TLR4,MyD88 and NF-κB in jejunum,thus reduced the inflammatory lesions in intestinal.Pithecellobium clypearia ex-tract also could significantly increase the abundance of beneficial microbial such as Parabacteroide and Prevotellaceae,while significantly decrease the abundance of pathogenic microbial such as Proteobacteria in cecum(P＜0.05)and improve the microbial diversity in intestinal.In summary,Pithecellobium clypearia extract could improve the structure of intestinal tissue and the gut barri-er function,as well as the microbial diversity in cecum,and also decrease the inflammatory lesions in jejunum,which is helpful to the intestinal health for yellow-feathered broilers.The present study provides scientific basis for the development of Pithecellobium clypearia as a safe feed additive in the future.