Abstract: Dietary fiber(DF)of Agrocybe aegerita was modified with cellulase and high temperature-high pressure treatment,the yield and physicochemical properties of soluble dietary fiber(SDF)before and after modification were compared. Two optimum modification conditions were obtained by orthogonal experiment on the basis of single factor. The results showed that the optimum conditions for cellulose treatment were determined as follows:The material to liquid ratio was 1:30,cellulase dosage was 1.5%,and the enzymatic hydrolysis time was 2.0 h. Under these optimal conditions,the yield of SDF was 4.9%. The optimal conditions for high temperature-high pressure treatment were determined as material to liquid ratio of 1:30,temperature of 125 ℃,and time of 50 min,giving an SDF yield of as high as 6.8%. Both cellulase and high temperature-high pressure modification can improve the physicochemical properties of DF. The DF treated by high temperature-high pressure was superior to cellulase in water holding capacity,swelling capacity,cation exchange capacity and glucose absorption capacity. SEM analysis showed that the surface area and surface pores of the modified DF increased significantly,which was consistent with the results of physical and chemical analysis.