Abstract: After decades of unremitting efforts, tumor immunotherapy has made significant progress. For patients with advanced cancer, significant clinical benefit has been achieved by blocking the T-cell immune checkpoint PD-1 or CTLA-4 receptor, significantly extending patients' survival. However, in the unselected population, the overall efficiency is still less than 20%, so it is necessary to explore new immunotherapeutics and treatment models. Small molecule-based immunotherapeutic methods have significant advantages in pharmacokinetics and drug utility, showing potential in early studies. This article will review the current status of small-molecule immunotherapy for tumors, in order to find more precise targets for immunotherapy.