Objective To explore the identification and diagnostic value of energy spectrum CT for benign and malignant lung lesions. Methods A total of 57 patients with pulmonary lesion examined by X-ray and chest CT from March 2015 to October 2017 were selected for the study. According to the pathological examination results, the patients were divided into benign lesion group (n=21) and malignant lesion group (n=36). The two groups were given energy spectrum CT imaging technique, and the images were analyzed and processed. The single-energy CT values of 40-80 keV compartments in arterial and venous phases, and the energy spectrum slope of 40-70 keV compartments in arterial phase, iodine base value and water base value and difference in arterial and venous phases were compared between the two groups. Results The single-energy CT values of 40-80 keV compartments in arterial and venous phases were lower in benign lesion group than those in malignant lesion group (P<0.05). There was a statistically significant difference in the energy spectrum slope of 40-70 keV compartments in arterial phase (P<0.05). The iodine base value and difference in arterial and venous phases were lower in benign lesion group than those in malignant lesion group (P<0.05). The water base value and difference in arterial and venous phases were higher in benign lesion group than those in malignant lesion group (P<0.05). Conclusion There are some differences in the energy spectrum CT findings of benign and malignant lung lesions. CT diagnostic results have certain reference value for clinical diagnosis.