The microfluidization was applied to modify the properties of soybean fiber in this study.The influence of pressure and the times that the sample was processed on dietary fiber was elucidated by particle size,specific surface area,water holding capacity (WHC),swollen volume (SV) and viscosity determinations.The results indicated that with the pressure increased from 60 to 140MPa,the granularities of the material decreased firstly and then increased.The minimum granularity was obtained when the sample was treated at 100MPa.The decrease of particle size and the occurrence of expanding in the materials caused a significant increase of specific surface area.