In gas insulated switchgear （GIS），very fast transient overvoltage （VFTO） is easily caused by disconnector operation.In order to simulate and analyze this electromagnetic transient phenomenon and its potential harm，the high-frequency oscillation zero-crossing factor is taken into account on the basis of the traditional method considering zero-crossing arc extinguishing logic.A detailed logical judgment process of arc extinguishing and arc reignition is proposed.A 1 000 kV GIS transient circuit model is constructed，and the simulation analysis on the model is carried out.The research results show that when the disconnector reignites the arc，the load side presents a ladder-shaped voltage response with different widths，and the peak overvoltage appears at the end of the bus，but the VFTO amplitude at the transformer inlet does not reach the insulation breakdown threshold.With the increase of residual voltage at the load side，the frequency of arc ignition also increases.Compared with the traditional models，the new model considering high-frequency oscillation zero-crossing arc extinguishing shows that the number of VFTO arc reignition increases by 40 times，and the amplitude increases by 0.27 p.u..The research provides a reference for an in-depth understanding of electromagnetic transient phenomenon in GIS and optimization of substation insulation design.