Abstract: With the popularization of high-resolution thin-layer CT, the detection rate of early asymptomatic lung cancer that manifests as solitary pulmonary nodules has significantly increased. The differentiation of benign from malignant nodules and histopathological classification are the keys to and challenges of clinical diagnoses, the accuracy of which is of great significance for treatment decision-making. Traditional CT evaluates nodules based on their size, density, and morphological characteristics with single modal imaging. Dual-energy CT achieves material separation based on attenuation differences in the same tissue at two different energy levels, which allows CT imaging to evolve from a single-parameter to multi-parameter measurements. This not only provides more valuable information for the early and accurate diagnosis of nodules but also facilitates measurements of tumor progression and heterogeneity. In addition, the combination of radiomics based on artificial intelligence and multi-parameter images by dual-energy CT has shown great potential in diagnosis, and the related investigations are in exploratory stages. This review will cover the application of dual-energy CT in the diagnosis of solitary pulmonary nodules, with a focus on the meaning of multi-parameter images for the ccurate diagnosis of pulmonary nodules. Further, the future directions of this diagnostic imaging technique are discussed as well.