Abstract: In this work,by means of particle size analysis,scanning electron microscopy(SEM),X-ray diffraction(XRD)and differential scanning calorimetry(DSC),the effects of two treaments of high speed jet(HSJ)with different pressure(60,100,140,180 and 220 MPa)on the particle size,microstructure,freeze-thaw stability,solubility and DSC curves of tapioca starch were investigated. The results showed that tapioca starch was treated by HSJ,the surface structure of granules was seriously damaged and tapioca starch was partly gelatinized,the size of its granules significantly increased,its solubility also rose,but its freeze-thaw stability was decreased. The HSJ treatment did not change the type of crystal structure of the tapioca starch,but reduced its crystallinity degree.