The electrostatic discharge phenomenon of the gas-solid interface is the inducement of charge accumulation on the insulation surface and the precursor of the flashover along the surface

which also seriously threatens reliability of the insulation structure. For revealing the electrostatic discharge mechanism and its influence factors further

the dust pattern technique is used in this paper to characterize the accumulated charge on the insulation surface of polymethyl methacrylate. The voltage amplitude and electrode structure are changed to simulate different operating environments and explore the charge distribution on the insulation surface as well as the development process of streamer. The experimental results show that under the influence of back discharge

the obvious differences in the appearance and external diameter of the charge pattern under the positive and negative polarity are existed

which causes polarity effect for the development process of the insulation along the surface. The difference in voltage and electrode structure leads to the variation of electric field distribution

and can eventually affect the streamer development and the charge accumulation process. The dust pattern also provides visual pattern data for analyzing the charge distribution and the development process of streamer along the surface of insulation materials.