Abstract: Starch nanoparticles were prepared from sweet potato starch using a purely physical method of high pressure homogenization. The effects of homogenization pressure, homogenization times, starch concentration on the yield of starch nanoparticles had been analyzed, then the orthogonal test was carried out.Scanning electron microscopy, particle size analyzer, fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were used to characterize the morphological, electrochemical, spectroscopic, crystal and thermal properties of starch nanoparticles. The results showed that under the condition of homogenization pressure 80 MPa, homogenization passes 25 times, starch concentration 3.2 g/100 m L, the yield of starch nanoparticles reached 46.12%.The starch prepared nanoparticles were spheric shape of average diameter of214.3 nm, and the basic chemical structure of starch nanoparticles didn't change, but the crystallinity and initial resolution temperature decreased.What's more, the absolute zeta potential of starch nanoparticles increased, so it had better capacity of dispersion in water.