Abstract: Objective: To study the roles of CT perfusion imaging and dynamic enhanced for diagnosis of lung nodule. Methods: The dynamic contrast-enhanced CT were performed with single-slice spiral CT in 34 patients with lung nodule (including: 17 cases of malignant nodule, 11 cases of benign nodule, and 6 cases of active inflammatory nodule). The CT perfusion imaging and dynamic enhanced CT were performed with two-slice spiral CT in 45 patients with lung nodule (including: 24 cases of malignant nodule, 13 cases of benign nodule, and 8 cases of active inflammatory nodule). According to dynamic contrast-enhanced examination, CT values of the nodules at different delay time were got to describe the time-density curve in all cases. The perfusion parameters, including Blood Flow, Blood Volume, Mean Transmit Time and Permeability Surface, were acquired with body perfusion-2 software, and they were analyzed and compared among three groups of lung nodules. Results: The time-density curve of the benign pulmonary nodules was fiat with enhancement only about 10 Hu. The malignant nodule increased rapidly at early time and maintained a plateau with decreased slowly in delay phase, with enhancement of CT value about 46 Hu. Whereas the active inflammatory nodule increased rapidly and come down also rapidly, with enhancement of CT value about 62 Hu. The values of blood volume and permeability surface in malignant and active inflammatory nodule are greater than that in benign pulmonary nodules. The values of blood volume and permeability surface in benign nodules are less than 6.5 mL/100g and 30 mL/100g min, respectively. Conclusion: CT perfusion imaging can provide quantitative information of blood perfusion within lung nodules, CT perfusion imaging and dynamic enhanced CT is helpful for differentiating lung nodules.