Abstract: The granular size,microstructure and digestibility of micronized tapioca starch with different time(0,15,30,45,60 min)were investigated by particle size analysis,scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR)and Englyst method,which can provide a theoretical basis for the research of micronization modified tapioca starch and its effect on digestibility. The results showed that the granular structure of starch was seriously damaged,and the starch granules agglomerated after the micronization treatment. When the time of micronization reaches 60 min,the particle size of starch increased from 13.50 μm to 36.17 μm and the A-type crystal structure was not changed,while the degree of crystallinity decreased from 21.33% to 1.14%. The intensities of the infrared(IR)absorption peaks at 3000~2800 cm^-1 and 1080 cm^-1 was decreased,indicating that the structure of tapioca starch was destroyed by micronization treatment,and the hydrogen bond interaction was weakened. The content of rapidly digestible starch(RDS),slowly digestible starch(SDS),and resistant starch(RS)in the native tapioca starch were 3.91%,44.71%,and 51.38%,respectively. After 60 min of micronization treatment,the contents of RDS and SDS increased to 6.87% and 45.91%,respectively,while the content of RS decreased to 47.21%,showing that micronization treatment could slightly change the digestibility of tapioca starch.