Patients with aldosterone-producing adenoma (APA) and cortisol-producing adenoma (CPA) show some similar clinical symptoms, and a large overlap of conventional imaging manifestations, which make the differentiation difficult. The purpose of our study was to explore the value of gemstone spectral imaging (GSI) dual-energy computed tomography (DECT) in differential diagnosis of APA and CPA, screen out meaningful energy spectral indicators and provide theoretical basis for the differential diagnosis of the two. We retrospectively analyzed the imaging and clinical data of 30 patients with APA and 27 patients with CPA who underwent GSI DECT in The First Affiliated Hospital of Zhengzhou University (a tertiary care institution). Patients were consecutively enrolled in this study, and the quantitative DECT parameters were compared between the APA and CPA groups by two-sample test. The diagnostic efficacies were evaluated by receiver operating characteristic (ROC) analysis. DECT parameters including CT (computed tomography) values at 40-70 keV in the arterial phase, concentrations of I (H2O) and fat (I) in the arterial phase, and the effective atomic number in the venous phase, were significantly different between the APA and CPA groups (all P<0.001), and the area under the curve (AUC) values are 0.80, 0.79, 0.88, 0.76, 0.82, 0.87, and 0.86. DECT quantitative parameters can effectively identify APA and CPA, the CT values at 40 and 60 keV in the arterial phase, the normalized CT value at 60 keV, the I (H2O), fat (I) concentration in the arterial phase and the effective atomic number parameter in the venous phase had valuable diagnostic performance.