The microstructure evolution and strengthening mechanism of WE54 alloy with different hard-plate rolling (HPR) processes were systematically investigated. The results suggest that the mechanical properties of the as-rolled alloys are significantly enhanced compared to those of the as-cast alloy. When subjected to three rolling passes at 450 °C and 490 °C, grain refinement occurs due to dynamic recrystallization. A mixed-grain structure is formed after a single pass rolling with a substantial reduction (65%) at 490 °C. The dynamic recrystallization (DRX) mechanism of the alloy during the HPR includes continuous dynamic recrystallization (CDRX), discontinuous dynamic recrystallization (DDRX), and twin-induced recrystallization (TDRX). The WE54 alloy exhibits the highest strength after three passes of HPR at 450 °C, with tensile strength and yield strength of 374 and 323 MPa, respectively. The significant improvement in the mechanical properties of the alloy is primarily attributed to fine-grain strengthening, solid solution strengthening, and dislocation strengthening.