Abstract: The optimization of process parameters for ultrasonic combined with enzymatic and alkali extraction of IDF（insoluble dietary fiber） from Passiflora edulis peel was developed using response surface method. On the base of single factor experiments，response variables including ultrasonic power，ultrasonic time，ultrasonic temperature，the total IDF yield were selected to carry out response surface optimal experiment，and the best condition of IDF extraction was optimized by Box-Behnken experiment design. The results showed that the optimum extraction was as follows：ultrasonic power of 355.5 W，ultrasonic time of 32.8 min，ultrasonic temperature of 37.3℃. Under these conditions，the extraction rate of IDF was 53.07%，and the product had canary yellow colors，its water holding capacity and expansibility were 8.97 g/g and 2.1 mL/g.