Abstract: There was more water infusibility pentosan in whole meal flour than in ordinary. WUP and protein had stronger interaction with each other, and the ineraction affected dough rheological properties and bread. The extracting process of wholemeal flour water infusibility pentosan by alkali method was studied. The process was optimized by response surface methodology ( RSM) and the optimum condition was determined as that when the ratio of solid to liquid, temperature and time were 1 ∶188 ( g /mL) , 65℃ and 3h respectively. The product obtained under that condition contains 95.33% of total sugar, 92.09% of pentosan and 3.24% of uronic acid.