This paper has been investigated the changes in the discharge characteristics and surface morphology of the MgO surface on both the indium thin oxide (ITO) and bus electrodes when the conventional (non-overlapped) and overlapped sustain waveforms are applied during the panel-aging process in alternating-current plasma display panel. For conventional sustain waveform, the strong surface discharge is confined within the ITO electrode, whereas for overlapped sustain waveform, the strong surface discharge is produced and spread toward the end of the bus electrode as well as the ITO electrode. It is demonstrated that the overlapped sustain waveform is a very effective aging waveform that can obtain the uniform surface morphology of the MgO thin film on both the ITO and bus electrodes.