The morphology of the top surface and the vertical section of single-domain YBCO bulk samples with c-axis parallel to the top surface have been clearly revealed. The sample with c-axis parallel to the top surface grows epitaxial from the seed (in the center) to the edge in all the four regions divided by grown cross traces on the top surface, but the growth style is different in the adjacent regions. If YBCO crystal grows along a (or b) axis in one region, it must be grow along c-axis in the adjacent regions. The grown traces on the top surface forms a 78° angle when the four regions meet each other. The clear traces are formed by the different growth rates, styles along c-axis and a (or b) axis and also the slightly height difference of YBCO crystal between adjacent regions.