To investigate the pathological damage of lung and peripheral blood damage in rats exposed to radon and its progeny, Sprague-Dawley rats were exposed to radon in multifunction ecological radon chamber with the cumulative dose up to 60, 90 and 120 WLM, respectively. The numbers and proportions of white cells in peripheral blood were measured meanwhile the degree of lung and its bronchus injury was observed. It was found that proportions of white blood cells increased in the proportion of granulocytes and decreased in the proportion of lymphocytes (,p,<,0.05). A series of pathological alterations were observed including hyperaemia and edema in the alveolus, emphysema, infiltration of inflammatory cells. The occurrence of different pathology, its scope and the serious degree, alveolar capillaries and incidence of thrombosis increased with the accumulation exposure dosage. As a result, radon and its progeny can increase the proportion of granulocytes and decrease the proportion of lymphocytes in peripheral blood cells. At the same time the serious degree of lung and its bronchus injury will increase with the increment of the accumulation exposure dosage.