<p>This study investigates the milling mechanisms of 7075-T6 aluminum alloy enhanced by ultrasonic impact, focusing on the influence of milling parameters. A three-dimensional milling model of the alloy was developed using ABAQUS finite element software. Single-factor experiments were conducted to examine the effects of milling speed, depth of cut, and feed rate on triaxial milling force, residual indent morphology, and residual stress. The results indicate a positive correlation between milling parameters and triaxial milling force, ranked in the order: feed rate (f) &gt; depth of cut (ap) &gt; cutting speed (Vc). Among these, the milling force in the x-direction (Fx(E)) is most affected by the feed rate, increasing by 55.16% as the feed rate rises from 0.03 to 0.14&#xa0;mm/r. Ultrasonic impact induces a hardened layer on the aluminum surface, featuring residual indentations, impact cracks, and micropits, which result in higher optical contrast at the indentation edges. SEM and EDS analyses reveal that at a milling speed of 83&#xa0;m/min, the oxygen mass fraction in the residual debris reaches 41.09%, indicating the formation of Al2O3. In contrast, at a feed rate of 0.03&#xa0;mm/r, the mass fractions of Al, Zn, Mg, and Cu in the indentations are higher, at 89.22%. The maximum residual compressive stress in the subsurface layer is significantly influenced by milling parameters, with the order of influence being depth of cut (ap) &gt; feed rate (f) &gt; cutting speed (Vc). Residual compressive stress increases by 149% when the depth of cut is increased from 15 to 35&#xa0;μm.</p>