Pancreatic ductal adenocarcinoma (PDAC) is a malignant tumor with aggressive biological behavior, difficult diagnosis at an early stage and dismal outcome. Recent investigations showed that the tumor microenvironment and immunomodulation are closely related to the occurrence of PDAC, and researches upon the biological environment may provide new strategies for the treatment of this lethal condition. The authors address the research progress in the field of PDAC microenvironment.