Urine can accumulate changes and reflect early physiological and pathological changes of various diseases, such as tumors. Therefore, urine is an ideal source for identification of early biomarkers. In this study, melanoma and prostate cancer-bearing mouse models were established by subcutaneous injection of B16 and RM-1 cells, respectively. Urine samples were collected at four time points during tumor growth. Based on dataindependent acquisition (DIA) technology, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for quantitative analysis. Compared with those before the injection of B16 cells, 38 human homologous differential proteins were identified, and 18 proteins were reported to be related to melanoma. Before the tumor was visible, there were 4 differential proteins, and all were reported to be related to melanoma. Compared with that before the injection of RM-1 cells, a total of 14 human homologous differential proteins were identified, and 9 proteins were reported to be associated with prostate cancer. Before the tumor was palpable, 9 proteins showed significant differences. There were significant differences between the two tumor-bearing models. Through the above experiments and analysis, we found that the urine proteome can reflect the changes in the development and provide early biomarkers of the two tumors and provide clues for the early clinical diagnosis of these diseases.Skin melanoma is one of the most common cancers in the world [1]. Melanoma is produced by the malignant transformation of melanocytes. This disease can occur in any part of the skin and mucous membranes. Melanoma easily metastasizes and is highly invasive and malignant, leading to high mortality. The diagnosis of melanoma is based on a combination of clinical and pathological techniques, including physical examination, histopathological examination and imaging examination. However, due to its variable histological morphology, with little or even no visible pigment, it is difficult to diagnose patients in the early stage and distinguish this condition from benign nevus in the clinic, which makes its early diagnosis difficult [2]. Early treatment of melanoma is mainly surgery, and advanced treatment includes chemotherapy, targeted therapy and immunotherapy. Compared with chemotherapy alone, targeted therapy and immunotherapy have significantly improved the survival rate of patients with advanced melanoma, but these two therapies are usually limited by the drug resistance rate and are not universally applicable [3,4]. The absolute survival rate of patients is still very low [5]. The 5-year survival rates of skin melanoma at stage I to IV are 97% (stage IA), 84% (stage IB), 68%, 55%, and 17% [6]. Therefore, early diagnosis can lead to early treatment and improve the survival rate of patients.Prostate cancer is one of the most common malignant tumors in men. In Europe and America, the incidence rate is highest among those of all cancers in males. The mortality rate is second only to that of lung cancer, ranking second fo...