In order to optimize brewers' grain fermentation technics for probiotics,the effects of 13 factors,such as urea,ammonium sulfate et al,on the total number of beneficial microbe in the probiotics,were studied by Plackett-Burman design and response surface methodology.The result showed that there were significantly relation among the total number of probiotics,urea,ammonium sulfate,fermentation temperature.The max predicted number of probiotics was 9.85×108CFU/g and the practical number was 9.73×108CFU/g when the urea concentration was 2.87%,ammonia s...