Objective To explore the value of iodine overlay image technique based on dual-source CT dual-energy for the diagnosis in the primary hepatocellular carcinoma patients undergoing transcatheter arterial chemoembolization (TACE). Methods The imaging data of patients with primary hepatocellular carcinoma after TACE treatment from September 2015 to November 2018 were retrospectively analyzed. All patients completed dual-source CT dual-energy examination and digital subtraction angiography (DSA). The imaging data of the patients were analyzed by conventional linear blending images and iodine overlay image. The results of DSA were taken as the gold standard. The data indexes measured by the two imaging methods were compared. The consistency between the two imaging methods and DSA was determined by Kappa statistics. Results A total of 31 patients were included, and 57 nodes were found under DSA examination. The image quality evaluation (P<0.05), sensitivity (95.35% vs. 69.77%), specificity (92.86% vs. 64.29%), accuracy (94.74% vs. 68.42%), positive predictive value (97.62% vs. 85.71%) and negative predictive value (86.67% vs. 40.91%) of iodine overlay images were higher than those of conventional linear blending images. The consistency between conventional linear blending images and DSA was low (Kappa=0.286, P=0.023), and the consistency between iodine overlay images and DSA was excellent (Kappa=0.861, P<0.001). Conclusions Iodine overlay image could avoid the iodide artifact effectively and evaluate the abnormal enhancement quantitatively and qualitatively in patients undegoing TACE. This method could obtain more information to help diagnose in clinical and evaluate the postoperative efficacy of TACE accurately and objectively.