Esophageal cancer is one of the common malignant tumors, and its incidence in China is high. Effective prevention and control is a focus and challenge due to difficult prevention and late diagnosis. The development of liquid biopsy technology represented by circulating tumor DNA (ctDNA) provides new insights for early diagnosis, treatment evaluation and prognosis monitoring of esophageal cancer. ctDNA detection method has high specificity and sensitivity, which can be used in tumor screening and diagnosis, and has high application value in judging prognosis and guiding treatment. This article reviews the detection technology of ctDNA and the research progress in the diagnosis and treatment of esophageal cancer.