This experiment was conducted to investigate and compare the effects of bacterial xylanase and fungal xylanase on villus morphology and intestinal somatostatin (SS) mRNA expression in yellow-feathered broilers. Three hundred and seventy-five 22-day-old in yellow-feathered broilers were randomly assigned to three groups with five replicates and twenty-five chicks in each pen. Broilers in three groups were fed diets supplemented with 0 (control group), 250 mL/t fungal xylanase (Exp Ⅰ) and 250 mL/t bacterial xylanase (Exp Ⅱ) in wheat-based diet. The experiment lasted for 28 days. Sample paraffin section staining method was adopted to observe the morphological structure of small intestine, and the expression of SS mRNA in duodenal and jejunal mucosa was measured by relative quantitative RT-PCR method. The results showed as follows: 1) the villus height of duodenum, jejunum and ileum showed a trend as Exp Ⅱ>Exp Ⅰ>control group. The villus height of duodenum in Exp Ⅱ was higher than that in control group (P<0.05), the villus height of other intestinal sections among the three groups were not significantly different (P>0.05). 2) The crypt depth of duodenum, jejunum and ileum showed a trend as Exp Ⅱ<Exp Ⅰ<control group. Compared with control group, the crypt depth of duodenum in Exp Ⅰ was decreased by 11.39% (P<0.05), and the crypt depths of duodenum and jejunum in Exp Ⅱ were reduced by 17.90% (P<0.01) and 15.61% (P<0.05), respectively, but the crypt depth of ileum among the three groups were not significantly different (P>0.05). 3) The villus height/crypt depth (V/C) ratio of duodenum, jejunum and ileum showed a pattern as Exp Ⅱ>Exp Ⅰ>control group. Compared with control group, V/C ratio of duodenum in Exp Ⅰ was increased by 21.94% (P<0.05), and V/C ratios of duodenum, jejunum and ileum in Exp Ⅱ were increased by 38.66% (P<0.01), 37.83% (P<0.01) and 25.58% (P<0.05), respectively. Furthermore, V/C ratio of duodenum in Exp Ⅱ was 14.41% higher than that in Exp Ⅰ (P<0.05). 4) Compared with control group, expression of SS mRNA of duodenum and jejunum mucosa in Exp I and Exp Ⅱ was reduced by 49.59% (P<0.01) and 52.49% (P<0.01), 6.83%(P>0.05) and 44.30% (P<0.05), respectively, but there was no difference between them (P>0.05). These results indicate that the supplementation of either fungal xylanase or bacterial xylanase in wheat-based diet can improve the small intestinal villus morphological development in difference degrees, and inhabit the expression of SS mRNA of intestnal mucosa in yellow feathered broilers. The effects of bacterial xylanase is equal to fungal xylanase.［Chinese Journal of Animal Nutrition，2011，23（2）：266-273］