High hydrostatic pressure (HHP) treatment, a nonthermal processing technology, was carried out to assess how this method affects the in vitro digestibility, physicochemical properties, and textural properties of tartary buckwheat starch (TBS). Pressurization at 120-480 MPa did not change the 'A'-type crystalline pattern of TBS. However, HHP treatment at 600 MPa contributed to a similar 'B'-type pattern. HHP treatment resulted in TBS granules with rough surfaces. Amylose content, pasting temperature, and thermostability significantly increased with increasing pressure, while relative crystallinity, swelling power, hardness, and viscosity decreased. Compared with native starch, HHP-modified TBS had lower in vitro hydrolysis, reduced amount of rapidly digestible starch, as well as higher levels of slowly digestible starch and resistant starch. These results suggest that HHP can efficiently modify the in vitro digestibility, physicochemical properties, and textural properties of TBS.