BAP1 is a member of the ubiquitin C-terminal hydrolases (UCH) subfamily of deubiquitylases with basic function of removing monoubiquitin or ubiquitin chains from the specific substrate proteins. As well, it is a key factor in regulating gene expression, cell cycle, cell differentiation, cell apoptosis and DNA damage response, dependent or independent of its deubiquitination function. Evidences have revealed that mutation or down-regulation of BAP1 can prominently increase the occurrence of cancers, including uveal melanoma, mesothelioma, renal cell carcinoma, breast cancer and lung cancer. Currently, the tumor spectrum and the pathogenic mechanism on BAP1 have not been illustrated clearly, and need to be further researched, which might bring a new opportunity in treatment of cancers.