Exosomes are extracellular vesicles formed by continuous invagination of cell membranes. They can transfer proteins, RNA, lipids, DNA, cytokines, transcription factors and other molecules of cell origin to recipient cells and carry out intercellular communication. Tumor cells can secrete more exosomes than normal cells, which can be isolated and detected in circulating plasma and play an important role in the development, metastasis, drug resistance and other processes of tumors. Programmed death-ligand 1 (PD-L1) is not only found in the tumor cell membrane, but also in the exosome membrane, namely exosomal PD-L1（ExoPD-L1）.The study shows that ExoPD-L1 can locally or remotely bind into programmed cell death-1 (PD-1) on the T cell membrane in the tumor microenvironment and cause T cell immunosuppression, promoting tumor progression. This review reviews the relationship between ExoPD-L1 and tumor microenvironment, its role in tumor immune escape and its potential biomarkers