In this paper

the 50kV/0.44 μF capacitor is subject to sampling test.The preliminary study on the life reliability of capacitor is performed for the first time in China and

on the basis of which the reliability of Marx generator is predicted.It is shown by the experiment that the capacitors’ failure is mainly the dielectric breakdown at the edge and the outlet position of electrode.It is thought by analysis that this is related to the strong electric field at the edge of electrode/dielectrics.The Weibull distribution feature parameters are obtained by the use of failure data fitting of capacitor.It is obtained that the average predicted life of such type of capacitor under 50kV is about 7 300 times and the mean time between failures（MTBF）of 66 capacitors in the Marx generator are about 221 times average in accordance with the failure probability of capacitor within 95% confidence interval.