Abstract: In this experiment,120 one- day-old Ross 308 broiler chicks were selected randomly and divided into 4 groups with three repetitions,with each repetition of 10 chicks.The basal diet was fed in the control group.And 100,300 and 500mg/kg ethanol extracts from Allium mongolicum Regel （AWE）were added to the basal diet in the experimental groups AWEⅠ,AWE Ⅱand AWE Ⅲ respectively.The effects of ethanol extracts from A.mongolicum on the development of small intestine mucous membrane in broilers were studied.The results showed that adding 500mg/kg AWE in the basal diet could significantly increase the villus length of duodenum of 28-day- old broiler chicks and the villus length of jejunum of 42-day- old broiler chicks（P0.05）.The villus width and the crypt depth between control group and experimental groups had no significant difference（P0.05）.Adding ethanol extracts from A.mongolicum to the diet significantly increased V/C ratio of duodenum in broiler chicks（P0.05）.V/C ratio of duodenum in each experimental group was significantly higher than that of control group （P0.05）.V/C ratio of the jejunum and the ileum of 28-day-old broiler chicks in each experiment group was significantly higher than that of the control group（P0.05）.The above results showed that adding ethanol extracts from A.mongolicum to the diet had certain promotion on the normal development of small intestine mucous membrane in broiler chicks and enhanced the absorption capability of small intestine mucous membrane of broiler chicks.And 500mg/kg AWE in diet had the best effect.