Pancreatic cancer is a highly-invasive malignancy, with an increasing incidence rate. Upon admission, most cases are diagnosed with advanced stage, complicated with unresectable locally advanced or metastatic diseases. Recurrence is commonly seen even in individuals undergoing radical resection. For high-risk groups, there is no widely-accepted screening method. Diagnosis, treatment evaluation and recurrence detection mainly depend on imaging examination. Effective methods are urgently required to assist diagnosis, efficacy evaluation and recurrence detection. Emerging technologies such as circulating tumor DNA (ctDNA), circulating tumor cells and exosomes have gradually matured and applied, which showcase potential advantages in the study of pancreatic cancer. In this article, research progress in the application of ctDNA in the early diagnosis of pancreatic cancer was reviewed.