The superconductivity and structure was studied in Y-Ba-Cu-O ceramics. BaCO3, Y2O3, CuO were mixed at a composition of YBa2Cu3O6.5, calcined at 900°C for 5 h, and sintered under various conditions. The critical temperature was 90 K for the ceramic sintered at 950°C for 10 h. The structure was analyzed with scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy.