The accumulation of radiation damage increases system free energy and triggers recrystallization, leading to the formation of High Burnup Structure (HBS) in uranium dioxide (UO2) fuel. While HBS formation typically involves gas bubble evolution, this study focuses solely on recrystallization-driven grain structure evolution, excluding gas bubble effects. Understanding this process is critical for evaluating nuclear fuel performance under irradiation. A phase-field model was employed to simulate recrystallization evolution, incorporating irradiation-induced dislocation energy into a conventional grain growth framework. Simulations examined recrystallized grain growth in both single-grain and bicrystal systems, revealing a strong correlation between grain growth and dislocation density. The model accurately captured recrystallized grain morphology and equilibrium structures, demonstrating consistency with theoretical predictions. The effects of temperature, dislocation density, and initial grain size on recrystallization evolution were also discussed.