Abstract: The vacuum gap is constituted of hemisphere plane.Under the single pulse high voltage, the discharging current waveform is captured with a digitizing signal analyzer DSA602A and ana lyzed in the theory.The axial electric field of the hemispherical top cathode is calculated in the va cuum gap of the certain size.Some films of high conjunctive intensity can be depositted with the optimal IBAD(ion beam assisted deposition)technological parameters.All films can bear high temperature treatment at 900 ℃,and they can still retain original surface condition after the bom bardment of the high energy microparticles at hundreds of times.The main parameters of single pulse discharging waveform show that the several films have improvement to the different extent about the voltage holding capability, the improvable extent is appeared by synthetic performance of the film material.