Traditional Chinese medicine (TCM) has been widely used in China and show effective in long history clinical practice. Many herbs or ingredients from TCM have shown immune immunomodulatory function and anti-tumor effects via targeting the immune system. Large retrospective cohort studies found that adjunctive therapy with TCM may improve overall survival of cancer patients. Meanwhile, advances from immuno-oncology (IO) make immunotherapy becoming a powerful tool for cancer treatment. There is a close relationship between TCM and IO. However, the knowledge of underlying mechanisms is limited due to the complexity of TCM with multiple ingredients acting on multiple targets. Herein, we present TCMIO, a comprehensive database of Traditional Chinese Medicine on Immuno-Oncology, for exploring the molecular mechanisms of TCM in modulating cancer immune microenvironment. Citing: Front. Pharmacol. 2020.11:439. DOI: 10.3389/fphar.2020.00439