The aim of this study is to assess the tumor heterogeneity of esophageal squamous cell cancer by dynamic FDG-PET (dPET). Thirty patients were enrolled in this study. Images were obtained after intravenous injection of 370 MBq of 18F-FDG for 1 h. The time-density curve of the standardized uptake value( SUV) was evaluated quantitatively by fractal analysis. Tumor fractal dimension (FD) maps were acquired, and the FD of the tumor was measured. There was a significant correlation between FD and the clinical response to adjuvant therapy. The FD reduction rates of adjuvant therapy were 23.23% in the responder group and 5.83% in the nonresponder group. FD may be a valid imaging biomarker for assessing the response to neoadjuvant therapy.