Tumor-infiltrating lymphocytes (TILs) are infiltrating lymphocytes in tumor tissues. After isolation, screening and amplification in vitro, they will be implanted into patients and play a specific killing effect on tumors. Since TILs have not been genetically modified and come from the body of patients, there will be relatively few adverse reactions. This is also the advantage of TIL treatment. In recent years, its curative effect on solid tumors began to show its sharpness. However, due to the limitations of the immune microenvironment and the mutation of antigens, TIL's development was slowed down. This article reviews the research progress, biological characteristics, preparation and methods of enhancing the therapeutic effect of tumor-infiltrating lymphocytes, their roles in different tumors and prognosis, and emphasizes the important value of tumor-infiltrating lymphocytes in anti-tumor.