Abstract: The present disclosure provides the use of BAZ1B_K426hy in the preparation of a product for tumor detection and belongs to the field of biotechnology. The present disclosure further provides a group of immunogenic polypeptides, including polypeptide A and polypeptide B. An anti-BAZ1B_K426hy polyclonal antibody is prepared by conducting mixed immunization on an animal with the immunogenic polypeptide. The polyclonal antibody can specifically recognize an endogenous protein BAZ1B_K426hy by enzyme-linked immunosorbent assay (ELISA)/Dot blot/Western blot, which is used for preparation of detection products for tumors and Williams syndrome.