High performance phase change optical recording disk has been developed by using an oxygen-doped Ge-Sb-Te recording layer. The 5X10(5) overwrite cycles were achieved with this 6 at.% oxygen-doped phase change optical recording disk. The transmission electron microscope observation shows that the crystal grain size was enlarged and the "self-sharpening effect" disappeared with increasing of oxygen concentration. It is thought that the oxygen doping made it easy to grow the uniform large grain size without the self-sharpening effect around the amorphous mark and therefore, the overwrite cyclability of the phase change optical recording disk was improved.