Abstract: The relative biological effect of neutron is high. Therefore, neutron radiation injures body quite seriously. Bone marrow is the most sensitive organ to neutron radiation. Low-dose neutron can injure bone marrow badly and lead to bone marrow form acute radiation sickness. There are a series of lesions in heraatopoiesis system, such as peripheral blood hemogram change, hematopoietic cell damage and bone marrow stromal cell injury. It is very difficult to cure neutron-induced damage of bone marrow. The primarily curable method is comprehensive symptomatic treatments. Cytokines are used at the right moment. Hematopoietic stem cell transplant is enforced to cure the very serious bone marrow form acute radiation sickness.