The enzymes-chemical method was used to extract the insoluble antioxidant dietary fiber (IADF) from the remaining orange pomace after oppressing juice. The single factor experiment and response surface optimization have carried out considering the clearance rate of DPPH free radical as the indicator. The results of response surface showed that the clearance rate of free radicals was best in the condition of liquid ratio 33.58 mL/g, protease dosage of 0.21 mL/g, amylase temperature of 67 ℃ and glucoamylase temperature of 64 ℃, and highest value was up to 3.520 mmol Trolox/100 g IADF.