Objective: To study the pulmonary perfusion characteristics of severe COPD patients by using the 320-detector row CT. Materials and Methods: Twenty patients with severe COPD who can’t receive pulmonary function test (PFT) due to the pulmonary bulla showed on X-ray and 35 normal subjects with suspicious nodules were enrolled. They were received lung scan using Toshiba 320-detector row CT with 80kV voltage, 70mA current, and AIDR image reconstruction. The pulmonary perfusion data was processed with the image post-processing software, and pulmonary artery flow (PAF), bronchial artery flow (BAF) and perfusion index [PI = PAF/(PAF + BAF)] and the time-density curve (TDC) were generated. PAF, BAF and PI and the semiquantitative parameters including time to peak(TTP), maximum slope (MS), enhancement amplitude (EA) of the TDC curves were compared between the severe COPD group and the normal group using the independent sample t test. Result: In this study, the total radiation dose of pulmonary perfusion was 4.02mSv per subject, lower than that of conventional CT lung scan. There were statistically significant differences between PAF, BAF and PI in the severe COPD group (76.7 ml.min/100ml, 20.7ml.min/100ml, 82.2%) and that in the normal group (102.4ml.min/100ml, 2.28ml.min/100ml, 98.8%) (P<0.001). TTP was significantly higher in the severe COPD group (14.9s) than that in the normal group (11.3s) (p<0.05). No significant differences were found in other semiquantitative parameters between the two groups (p>0.05). Conclusion: Pulmonary perfusion characteristics between the severe COPD patients and normal people are distinct. There is a compensatory increase of bronchial artery in the severe COPD patients. The pulmonary perfusion characteristics of the severe COPD patients who can’t receive the PFT can be assessed by using 320-detector row CT with a low radiation.