In order to solve the problem that serious insulation fault caused by free pulsation of spherical metal particles in GIL, an experimental platform proportional shrunken according to GIL device is set up on the basis of analyzing the force of metal particles. The movement locus of metal particle and jumping field are filmed and recorded. The generality of the experimental results is guaranteed through multiple repetitive experiments. The results indicate that the particle jumping field is determined by the radius of the particles while the material is fixed. The gas pressure and the voltage polarity almost have no effect to the jumping field. The jumping field intensity decreases gradually with the increase of the quantity of neighboring particles. The pseudo resonance phenomena and firefly phenomena may appear when spherical particle moves in DC GIL. The probability of firefly phenomena increases with the increasing particle radius. The jump rate of the particles near the insulator is faster than that of the particles in the middle of the high voltage conductor. Multiple particles will cause the time-divided jumping phenomena and the movement locus is basically similar to the single particle.