<p>Potassium salts, as an important strategic resource, contain weakly cemented crystals and distinct bedding structures that make them highly sensitive to dynamic disturbances during mining activities. High strain-rate loading can rapidly modify the internal stress field of potash rock, leading to deformation, crack initiation, and eventual failure. To investigate these dynamic responses, dynamic Brazilian splitting tests were conducted using a split Hopkinson pressure bar (SHPB) system across four strain-rate ranges: R1 (50.2–55.8&#xa0;s⁻¹), R2 (91.5–100.3&#xa0;s⁻¹), R3 (142.6–155.9&#xa0;s⁻¹), and R4 (198.6–206.5&#xa0;s⁻¹). High-speed imaging combined with digital image correlation (DIC) was used to capture the full crack propagation process and strain evolution on the specimen surfaces. The results show a clear strain-rate strengthening effect in potash. As the strain rate increased from 50.2&#xa0;s⁻¹ to 206.5&#xa0;s⁻¹, the fracture mode transitioned from pure tensile failure to mixed tensile-shear failure, accompanied by a strain-localization shift from compressive zones at the incident end toward tensile regions near the specimen center. Both crack opening velocity (COV) and crack propagation velocity (CPV) exhibited strong strain-rate sensitivity. Energy analysis further revealed that the proportion of dissipated energy increased significantly with strain rate, indicating enhanced energy consumption during internal crack propagation. SEM observations reveal that, at high strain rates, cracks preferentially initiate along weak grain–boundary interfaces and subsequently develop with stronger transgranular fragmentation, ultimately resulting in a coupled intergranular–transgranular fracture pattern. These findings provide multi-scale insight into the dynamic tensile failure of potassium salt and offer a theoretical basis for safer blasting design, stability control of surrounding rock, and sustainable, high-efficiency potash extraction.</p>