Abstract: With the rapid development of mass spectrometry (MS)-based proteomics technology, the application of proteomic methods to find new tumor biomarkers has gained significant research interest. The waste eliminated by blood under the control of homeostatic mechanisms in various forms is collected in urine, which can be used to identify changes in the human biological system and the state of diseases. Compared with blood samples commonly used in clinical testing, urine samples have many advantages, such as simple and stable composition, ability to be continuously collected, and high detectability of low-abundance proteins. The low detection limit for proteins of interest in urine makes it ideal for tumor biomarker research. The proteins contained in urine are mostly from secretion; therefore, these proteins may also be good biomarkers. In this review, we summarize the research progress on MS-based urinary proteomics for discovery of tumor biomarkers and systematically analyze the candidate molecules of urinary protein markers for common tumors.