Four kinds of YBa2Cu2Ox (YBCO) superconducting powders with different particle sizes, shapes and different amounts of twins have been prepared in this work. The density, grain sizes, XRD of phase composition, configuration of twins of the ceramics have been investigated. The relation between the characteristics of YBCO powders and the microstructure, current density of the bulk materials are also discussed. In contrast to the YBCO powder prepared by solid state method, the YBCO powders through the improved coprecipitat ion approach have less impurities, smaller particle size and much more amounts of twins, as well as the sintered pellets show a higher density, an orthorhombic single phase, and moreover, the pellets have finer grain boundaries and well developed twins. As a result these samples exhibit current densities (about 1500 A/cm2) higher than those prepared by solid state method. Using BaOx instead of BaCO3 as the starting material, a more dense bulk YBCO ceramics with orthorhombic single phase and Jc (about 1,000 A/cm2) can have also been fabricated by solid state mat hod.