Objective To observe the protective effect and possible mechanism of Bushen Jiedu Fang（ 补肾解毒方） on mice with radiation injury. Methods Randomly divided mice of TLR4 gene knockout（ TLR4- /-） and none knockout（ TLR4 + /+） into blank control group

radiation model group and Chinese medicine group. Gave normal saline 0. 2 ml to mice in the blank control group and the radiation model group

and the Chinese medicine group was given Bushen Jiedu Fang 13. 50 g /（ kg·d） after adaptive feeding for 7 days. Mice in all groups except the TLR4 + /+ and TLR4- /- blank control group were given one-time60 Co γ ray 6Gy dose exposure after 11 days of gavage. Each group continued to receive 14-day gavage of above dose the second day after exposure. Observed the survival condition of mice after radiation exposure. Recorded the body weight and the weight of thymus and spleen

on the first

14 th

and 30 th day after radiation. Calculated thymus coefficient and spleen coefficient. Results TLR4 + /+mice in the radiation model group which died 2 to 14 day after radiation exposure counted up to 41 in total

while that of the Chinese medicine group counted up to 15 mice during 7 to 10 day after radiation; TLR4- /- mice in the radiation model group which died 5 to 13 day after radiation exposure counted up to 39 in total

while that of the Chinese medicine group counted up to 38 mice during 4 to 13 day after radiation; Compared to the same mice type in the blank control group

thymus coefficient and spleen coefficient of mice in the radiation group and the Chinese medicine group decreased to different degrees one day after treatment（ P < 0. 05 or P < 0. 01）. Thymus coefficient and spleen coefficient of TLR4 + /+ and TLR4- /- mice in the Chinese medicine group 14 and 30 day after radiation remarkably increased compared to that of this group one day after treatment（ P < 0. 05 or P < 0. 01）. Thymus coefficient of TLR4 + /+ mice in the Chinese medicine group 14 and 30 day after radiation remarkably increased compared to that of the radiation model group（ P < 0. 05 or P < 0. 01）; But thymus coefficient and spleen coefficient of TLR4- /- mice in the Chinese medicine group had no statistical difference with that of the radiation model group（ P > 0. 05）.Conclusion Bushen Jiedu Fang may remarkably decreased nuclear radiation injury and protect immune organ through TLR4 signal passage. It had good radiation-defending function.