Abstract: Some results of plasma erosion opening switch (PEOS) experiment on EPA 74 pulseline accelerator 10.5MV.6kA) are described in this paper.Three plasma guns and a magnetic insulation transmission line (MITL) with the resistance of 1 33 Ω are used.The experimental results show that prepulsing voltage of the diode decrease from 60kV to less than 10kV and the x-ray dose increases by 77°.at one meter in front of the target by u.sinc PEOS.