In C57BL/6 mice subjected to 6 Gy x‐ray irradiation, JAE significantly alleviated lymphocytopenia (p < 0.05, 74.31% alleviation), attenuated lung damage, and mitigated oxidative stress by enhancing SOD (41.70% increase) and CAT (10.43% increase) activities while suppressing MDA levels (13.59% decrease, all p < 0.05). The gene discussed is CAT; the disease is lymphopenia.