objective To evaluate the value of HRCT on differential diagnosis of a rat model of pulmonary fibrosis induced with bleomycin A5 and to replicate a rat model of pulmonary fibrosis for radio imaging study to investigate pathogenetic mechanism of pulmonary fibrosis. Methods In 50 of 60 male Sprague Dawley rats bleomycin A5 was given through the trachea, and the other 10 received same volume of normal saline. After 28 days, HRCT and pathological examination of the lungs were performed, and the changes were correlatively studied. Results HRCT showed pulmonary fibrosis in all the 50 rats treated with bleomyein, including ground glass opacity, nodular shadow, abnormality in bronchio vasarlar linings, pleural thickening, and in some with beehive like changes. Lung fibrosis was corroborated by pathological sections. Conclusion HRCT can be used to diagnose pulmonary fibrosis of living rats. It is a simple, accurate, reliable, and it can give good representation.