A modified driving waveform in AC plasma display panel is proposed to improve the address discharge characteristics applying the additional pulses on the sustain electrode during an address period. After a reset period in the driving scheme of an AC PDP, the electrons are accumulated on two front electrodes and the ions are accumulated on the address electrode. Among the accumulated wall charge on three electrodes, the electrons on the scan electrode and the ions on the address electrode are mainly used for the address discharge triggering when the scan and address pulses are applied simultaneously during an address period. Meanwhile, since the constant bias voltage on the sustain electrode is only maintained during an address period, the wall charge on the sustain electrode a little contribute to an address discharge triggering. In this sense, if the electrons on the sustain electrode during an address period are utilized, the improvement of the address discharge characteristics is expected. Therefore, in this study, the additional negative going pulses are applied to the sustain electrode while the scan and address voltages are changed during an address period. In addition, the address discharge characteristics are investigated in accordance with the various voltage height and pulse applying time. Consequently, the production time of an address discharge can be reduced approximately 200ns under the optimal driving condition compared with the conventional driving waveform.