Abstract: Soybean residue produced by enzymatic aqueous processing of soybean oil was used as the raw material to prepare phytic acid through the steps of ultrasonic-assisted extraction and compared with shaking extraction. Optimal ultrasonic conditions were determined by single factor and orthogonal tests,selecting ultrasonic power,ultrasonic temperature and ultrasonic time. On the basis of ultrasonic treatment,optimal extraction conditions of phytic acid were studied by using Box-Behnken central composite design and response surface analysis theory. Results showed that the optimal ultrasonic conditions were ultrasonic temperature50 ℃,ultrasonic power 500 W and ultrasonic time 20 min. The optimal extraction conditions were acetic acid concentration 4.1%,ratio of solid to liquid 1∶17 g/m L,extraction temperature 64 ℃,extraction time 33 min. Under these conditions,the average phytic acid yield was 1.23%,which was higher than that of shaking extraction by 41.3%.