Dynamic high-pressure microfluidization (DHPM) technology was employed to modify the properties of proso millet starch and expand its applications. The effects of DHPM treatments at pressures ranging from 40 to 200 MPa on the multiscale structure and physicochemical properties of the starch were systematically investigated. Scanning electron microscopy(SEM)， differential scanning calorimetry (DSC)， fourier transform infrared spectroscopy (FTIR)， X-ray diffraction (XRD)， and rheological analyses were used to comprehensively elucidate the modification mechanism of DHPM. The results showed that DHPM treatment pressure had a significant interval effect on the modification of proso millet starch. At 40-80 MPa， starch granules showed surface roughening with D50 increasing from 10.20 μm to 13.10 μm and size distribution span widening from 1.19 to 1.49. Higher pressures (120-200 MPa) caused deformation and structural collapse， increasing D50 to 15.45 μm (51.47% increase). The 120 MPa treatment improved swelling power by 42.13%， enhanced the storage modulus， and increased the peak viscosity by 19.8%. Thermodynamic analysis showed that the gelatinization onset temperature decreased with pressure， with maximum enthalpy (14.95 J/g) at 40 MPa. Molecular structure characterization confirmed that the 80 MPa treatment induced changes in the short-range order (R1047/1020) of starch molecules. Crystallinity exhibited a ｀V'-shaped trend (40-120 MPa)， followed by a reduction at 160-200 MPa. These findings provide a theoretical basis for the development of physical modification technologies and functional applications of starch.