Abstract: In order to explore the mechanism by which stress affects the growth of broilers, this trail was designed to investigate the effect of glucocorticoid, one hormone released when animal stressed, on disacchridase activities and mucosa morphology in jejunum of broilers. Thirty-six 21-day-old Arbor Acres broilers with similar weight was randomly assigned into four groups, three of which was injected with 1 mL dexamethasone-saline solution (containing dexamethasone 0.1, 1 and 5 mg/kg BW, respectively). The dexamethasone is a kind of drug like glucocorticoid. The control group was injected with 1 mL saline solution. The result showed that (1) The dexamethasone restrained the growth of broilers significantly, and the effect is depended on the dose of dexamethasone (P<0.05). (2) There is no significant differences found in both sucrase and maltase activities between control group and injected groups (P>0.05). (3) The dexamethasone decreased the villus height, the absorption area and the value of villus height/crypt depth in broilers' jejunum significantly (P<0.05). The crypt depth of the group injected with dexamethasone 5 mg/kg BW was significantly deeper than that of control group (P<0.05). But dexamethasone don't have significant effect on the villus width and lamina propria mucosae thickness(P>0.05). The results suggest that the reason of growth restrain of broilers caused by stress may be related to the secretion of glucocorticoid which gives rise to the decreases of villus height, absorption area and the increase of crypt depth , and then impairs the absorption function of intestine.