This paper deals with overvoltages induced in the gas insulated substation （GIS）

For lightning overvoltages in the typical GIS substations

the paper gives the detailed results calculated by Electromagnetic Trasients Program.On the base of the calculation some suggestions for protection from these overvoltages and insulation co-ordination are proposed.There is a kind of overvoltages which may be rather critcal for GIS

that is the switching surges with high frepuency produced by operation in the main circuit.zinc-Oxide arresters have been found more effective than conventional surge arresters.