B-type potato starch was selected as the test object to promote the nanocrystallization of starch granules by high static pressure combined with hydrochloric acid hydrolysis. Polarized light microscope， X-ray diffraction analyzer， Fourier infrared spectrometer and other instruments were used to analyze the size， remote structure and proximal structure of starch granules. The results showed that the optimal hydrolysis time of potato starch was 12 h， the hydrolysis rate reached 10.47%， and the molecular mass was 1.628×1044 ku. However， through HHP synergistic acid hydrolysis， the hydrolysis rate reached a maximum of 13.16% and the molecular mass dropped to 0.236×1044 ku after treatment under the optimal condition of 400 MPa for 30 minutes. This indicates that pressure-assisted acid hydrolysis can greatly improve the hydrolysis efficiency of starch. Intermittent HHP treatment (400 MPa， 5 min/d) for 6 weeks resulted in a maximum hydrolysis rate of 30.09%， the large particles of potato starch were significantly reduced， the small particles were significantly increased， and the number of nano-sized (D<1 μm) starch particles was significantly increased by 19.7%. RC (Relative crystallinity) reached 52.10%， indicating that HHP synergistic acid hydrolysis could promote the nanocrystallization of starch granules.