Soluble dietary fiber was obtained from insoluble dietary fiber of corn bran by treatment with a celluclast.Insoluble dietary fiber is subjected to a sodium hexametaphosphate solution or high pressure treatment in order to enhance enzymic access and soluble dietary fiber production.The results showed that high pressure treatment was most useful to increase the yield of soluble dietary fiber,and high pressure treatment condition was 121℃,3 h.The reaction parameters affecting the soluble dietary fiber,such as substrate concentration,enzyme loading,pH,reaction temperature and reaction time,have been investigated.The maximum soluble dietary fiber production was observed after 11 h incubation of enzyme loading 2%,substrate concentration 40 g/L,temperature 55 ℃,and pH 4.0.The obtained yield of soluble dietary fiber was 10.37%.