Dynamic ubiquitination in eukaryotes either enters proteins into the 26S proteasome degradation pathway or functions in signal transduction, and therefore regulates protein stability, localization and activity, thus participates in transcription, cell cycle, inflammation, tumor, immunity and other functions. Ubiquitination modification is a reversible process, which is regulated by ubiquitin ligases (E3s) and deubiquitylases (DUBs). DUBs mediate the deubiquitination of substrate proteins, regulate protein functions, and participate in various cellular processes. The protein abundance, localization and catalytic activity of deubiquitylases are strictly regulated. During the occurrence and development of tumors, many important tumor-related proteins are regulated by deubiquitylases, and dysfunction of deubiquitylases also affect DNA damage repair, apoptosis, autophagy, molecular signaling pathways and chromatin remodeling, which modulate the process of cell growth, invasion and metastasis in tumors. Therefore, DUB is an important protein family involved in tumorigenesis, and is potential drug targets. Many small molecule inhibitors have been used in the research of anti-tumor treatments. This article mainly summarizes the regulation mechanism of ubiquitin molecules, ubiquitin chain specificity, and deubiquitinating enzyme system in tumors, and provides basis for the design of clinical drug targets and diagnostic indicators.