Mice were whole-body exposed to X-rays with absorbed dose of 6 Gy and sacrificed on the 1st, 3rd and 7th day by cervical dislocation after irradiation, respectively. The number of red blood cells and white blood cells in peripheral blood, the index of thymus and spleen, the micronucleus rate of bone marrow polychromatic erythroblasts (PCE) and the level of antioxidant of liver were determined. It was observed that white blood cells decreased, the index of thymus and spleen also decreased meanwhile both of the micronucleus rate of bone marrow PCE and level of lipid peroxidation of liver increased at 24 h after irradiation. However, the index of thymus was up slightly on the 7th day after irradiation, while the PCE and the level of lipid peroxidation of liver got down slightly. The other index of injured mice increased continually with time.Cited