<p>Gradient-hardened aluminum alloy possesses both strength and toughness, but its dynamic plastic deformation mechanism under impact load has not been understood. To investigate the surface microstructural evolution of gradient-hardened aluminum alloy under high-strain-rate load, this work employed the Laser-induced Particle Impact Test (LIPIT) to introduce high-strain-rate plastic deformation on the gradient-hardened 6061-T6 aluminum alloy prepared by Ultrasonic Shot Peening (USSP). The microstructure and texture features at the crater site were analyzed. The results indicate that LIPIT propelled particles with a diameter of 500&#xa0;μm to a velocity of 60&#xa0;m/s, which induced a strain rate of 1.2 × 10⁵ s^-1 in the surface layer of the target material. The active {111}&lt;110 &gt; slip system in the gradient-hardened 6061-T6 aluminum alloy facilitates the proliferation and rearrangement of dislocations under dynamic impact, leading to the formation of new boundaries and subgrains, which further contribute to grain refinement. The texture analysis reveals that the USSP-induced rolling texture transforms into {111}&lt;110 &gt; and {111}&lt;112 &gt; shear textures under LIPIT, with a total proportion of 38.7%. The dynamic plastic deformation mechanism of the gradient-hardened 6061-T6 aluminum alloys under LIPIT involves grain refinement, subgrain formation, and texture transformation driven by dislocation slip.</p>