Abstract:Poria cocos residue were fermented by Lactobacillus bugaicus and Streptococcus thermophilus（ratio 1 ∶ 1） to prepared dietary fiber （DF）. On the basis of single factor experiment， effects of amounts of fermenta－ tion temperature， time and inoculum were studied via Box-Behnken response surface methodology. And then formula optimization of cookies was determined by mixture design. Study results showed that the optimized ex－ traction parameters were fermentation temperature 40 ℃， fermentation time 20 h， inoculum 6 %. Under the conditions， the yield of prepared DF was（67.12±0.18）%. The water holding capacity， swelling capacity， water binding capacity of the prepared DF were（7.32±0.23） g/g，（5.31±0.08） mL/g，（5.65±0.19） g/g， respectively. The optimized formula of cookies was confirmed to be as followings： DF addition 5.4 %， egg addition 14.5 %， butter addition 24.0 %， and sugar addition 11 %. After Poria cocos residue fermentation， the purity and physic－ ochemical properties of the DF were improved， which indicated that fermentation method was a feasible method of DF preparation. And cookies could significantly enhance taste. This study could be used as a reference for the development of Poria cocos residue.