In the paper,YNB culture with high concentration of glucose and fructose was used for the growth of Saccraomyces cerevsiae. It showed that huge changes of metabolism in Saccraomyces cerevsiae had occurred,such as the Crabtree effect,the inhibition of aerobic respiration and the breakage of the TCA cycle,which caused the secretion of citric acid,α-ketoglutarate and malate out of the cell and the increase of the by-product concentration like lactic acid at the beginning of fermentation. Then,the sugar was consumed gradually as the process went on,which led to the second TCA cycle,and also made citric acid,α-ketoglutarate and malate entering into the cell consequently. To summarize,the mechanism of Saccraomyces cerevsiae cultured under high concentration sugar was profiled,and could serve as the theoretical support to beer manufacturers.