Abstract: In order to increase functional sugar yield from corn bran by- product of corn starch wet milling,corn bran had been taken as raw material in the experiment. The optimal conditions with ultrasonic- microwave synergistic extraction of functional sugar was studied.The sulphuric acid concentration,extraction time,microwave power and material- to- liquid ratio were selected by single factor test. The CCD center combine experiment was designed according to the single factor test results.The reducing sugar content was index value,while the best technology parameter of extracting functional sugar would be determined by the response surface method. Hydrolysate was analyzed by HPLC. The results showed that the reducing sugar content was 65.82% when the sulphuric acid concentration was 3%,extraction time 60 min,microwave power 500 W and material- to- liquid ratio of 1 ∶ 28( g /m L),which was higher than 20.72% without ultrasonic-microwave.The analysis of acid hydrolysates by HPLC indicated that the hydrolysates were composed of D- glucose,D- xylose,D- galactose,L- arabinose and D- fructose. The relative content of D- glucose was 17.04%,D- xylose was 49.06%,D- galactose was 2.64%,L- arabinose was 30.13%,and D- fructose was 1.13%.