A novel laser-processing technique that produces bulk YBa2Cu3Ox (123) plates has been developed. Through the application of a square CO2 laser beam with uniform energy density distribution to the surface of 123 powder compact, a single piece of ribbon-like plate is produced. This plate may be separated from the powder compact after laser scanning. The width of the plate is approximate to 6 mm, while its thickness is 0.1-0.2 mm. Powder X-ray diffraction indicates that laser-treated samples contain both orthorhombic and tetragonal 123 phases, as well as Y2O3 (200), Y2BaCuO5 (211), BaCuO2 (011), and CuO (001) phases. Scanning electron microscopy reveals a pattern of phase segregation along the transverse cross-section after solidification of the plate. After oxygen annealing of a single ribbon piece, T-c is found to be 90 K. This technique may be applicable to the mass production of 123 bulk superconductor by continuous melting of 123 powders. In addition to its potential for practical applications, the laser technique also helps to explain the complex phases and microstructure formation during melting and solidification of laser-melted 123 liquid. A model relating the microstructure to the thermal history inside the laser-affected region and to the phase diagram of incongruently melting 123 material has been developed to analyse phase formation during laser melting and solidification processes. Reasonable correspondence between theoretical analysis and experimental results was obtained.