The application of xylanase in functional beer was investigated.The results showed that the addition of xylanase in beer fermentation process could promote the formation of xylo-oligosaccharide(the addition of neutral xylanase had the best effects).Meanwhile,the best technical parameters for the addition of neutral xylanase were summed up as follows: neutral xylanase added at the beginning of protein rest(feed temperature rose to 5 0℃ at that time),the addition level was 110 U/g,as a result,the yield of xylo-oligosaccharide in barley beer was as high as 0.621 g/L.