The invention relates to a tumor-specific antigen TSP70 and an application thereof. The tumor-specific antigen TSP70 has an amino acid sequence shown in SEQ ID No. 1. The invention also provides the application of the tumor-specific antigen TSP70 of non-small-cell lung cancers, pancreatic cancers, ovarian cancers, mammary cancers and the like in preparation of diagnostic reagents for tumors such as the non-small-cell lung cancers, the pancreatic cancers, the ovarian cancers and the mammary cancers. The invention provides the novel tumor-specific antigen TSP70. The antigen has high expression positive rate in tumor cells of the non-small-cell lung cancers, the pancreatic cancers, the ovarian cancers, the mammary cancers and the like of human and also has high expression specificity; proven by an immuno-electron microscope, a protein of the TSP70 is located in cell membranes, cytoplasm and cell nuclei of cells; and the antigen can be used for preparing the diagnostic reagents for the tumors such as the non-small-cell lung cancers, the pancreatic cancers, the ovarian cancers and the mammary cancers as a standard substance and can also be used for preparing drugs for treating or preventing the tumors such as the non-small-cell lung cancers, the pancreatic cancers, the ovarian cancers and the mammary cancers.