This study investigates the effects of ultrasound synergistic pH shift modification on the structural and functional properties of Hericium erinaceus (HE) proteins. The modification resulted in significant changes in the molecular structure of HE proteins, including increased solubility (49.69 % at pH 1.5 and 61.30 % at pH 12.5), enhanced surface hydrophobicity (from 721.00 to 3377.00), and the exposure of free sulfhydryl groups, which rose from 9.3 μmol/g in the control to 19.9 μmol/g at pH 12.5. The modification also led to a reduction in particle size, improving oil-holding capacity and foaming properties, with foaming stability increasing from 10.5 % to 60.3 % at pH 12.5. Furthermore, the emulsification activity was significantly enhanced (187.5 % at pH 12.5). Rheological analysis revealed that ultrasound-modified proteins exhibited improved flow stress and gelation properties, with a shear recovery rate of 65.71 %. In 3D printing applications, the modified HE proteins demonstrated better printability, structural stability, and mechanical integrity, attributed to the enhanced molecular interaction and gelation properties. These findings suggest that ultrasound-assisted pH shift modification effectively alters the structure and functionality of HE proteins, making them suitable for use as a versatile raw material in food applications, particularly in 3D food printing.