Exosomes are small vesicles with a diameter of 30-150 nm secreted by cells, which can be used as signal carriers to transfer nucleic acids, proteins, lipids and other functional substances to the recipient cells and play a role in cell communication. Hepatocellular carcinoma is the fourth most common cause of cancer-related death worldwide. Studies have shown that long non-coding RNAs (lncRNAs) are involved in the development and progression of many types of tumors. Our present study found that linc-FAM138B was reduced in HCC tissues and cell lines, low expression of linc-FAM138B indicated a poor prognosis in HCC patients. Interestingly, linc-FAM138B could be packaged into cancer cells. And exo-FAM138B inhibited the proliferation, migration and invasion of HCC cells. Furthermore, linc-FAM138B sponged miR-765 levels. And exo-si-FAM138B promoted HCC progression, while deletion of miR-765 reversed the role of exo-si-FAM138B. In vivo tumorigenesis experiments showed that exo-FAM138B suppressed HCC growth via modulating miR-765. In conclusion, exo-linc-FAM138B secreted by cancer cells inhibited HCC development via targeting miR-765, which provided a new idea and perspective for in-depth understanding of the complex signal regulation in HCC process.