<p>Peripheral coarse grain (PCG) is a prevalent issue in aluminum alloy extrusions, closely linked to die structure and significantly affecting mechanical properties. However, the mechanism by which the die cavity influences material flow and PCG formation remains unclear. The impact of PCG on both dynamic and static mechanical properties, as well as the fracture mechanism of extrusion parts, has yet to be elucidated. These two issues impede the optimization of die structure and the enhancement of mechanical properties in extrusion parts. To address it, the influence of die cavity structured by different die-face angles on PCG was investigated using 2195 Al–Cu–Li alloy as a case study. The formation mechanism of the PCG was elucidated from the perspective of deformation stored energy by means of numerical simulations and physical field tracking techniques. The critical energy condition inducing PCG was also determined. The fracture mechanisms of sample containing PCG were revealed through <i>in situ</i> SEM tensile tests and fatigue tests. The results indicate that the thickness of PCG layer exhibits a positive correlation with the deformation stored energy accumulated along the material flow path. By designing the die surface with an appropriate inclination, the stored energy can be effectively reduced, thereby resulting in a thinner PCG layer. The faster propagation of intergranular crack within the PCG is the primary reason for reduction of static mechanical properties. However, the influence of peripheral coarse grain (PCG) on dynamic fatigue performance is inconsistent. At low stress amplitudes, PCG significantly reduces fatigue life, whereas at high stress amplitudes, its impact on fatigue life is minimal.</p>