Due to the characteristics of the closed structure of the transmission pipeline, VFTO is easy to appear in gas-insulated switchgear (GIS), which causes serious surface charge accumulation of insulators in equipment. Studying the solid-gas interface charge accumulation mode under impulse is of great significance in promoting pipeline power transmission systems development. In this paper, based on the rapid change of surface charge accumulation under repetitive impulse voltage, the ion mobility under impulse voltage is modified, and the numerical calculation model of surface charge accumulation is constructed. The changes of surface charge density distribution, surface potential distribution, and surface electric field of the epoxy sample under impulse voltage were calculated. The results show that the surface charge of the sample will accumulate obviously and gradually reach saturation under dozens of repetitive impulses. The distortion rate of the electric field caused by the surface charge is about 9.8 %. The obvious distortion of the surface electric field is an important reason for the decrease of surface flashover voltage.

suraface charge,GIL/GIS,impulse voltage,solid-gas interface