The priming discharge characteristic at the reset period in the ADS drive method of PDP was experimentally analyzed in this research. The amount of wall charge accumulated by the discharge and the accumulated time are unrelated to the priming pulse width. The self-erase discharge by excessive wall charge is related to the amount of wall charge by the priming discharge and this is related to space charge generated by the priming discharge. From the experimental result, in the optimized priming condition the plus width is 8$mutextrm{s}$ and the voltage is about 163V. The space charge which helps the self-erase discharge exists during about 16$mutextrm{s}$ immediately after generating the priming discharge. Therefore, it is suitable within 16$mutextrm{s}$ of the priming pluse width for the effective reset process.