This paper describes an investigation into the influence of charge accumulation caused by applied HYDC on impulse flashover level of spacers in compressed SF6Results indicate the polarity effects of such influences.The magnitude of effect depends on the duration of applied HVDC and its value.This can beexplained by the influence of charge accumulation.For the spacers with corrugated surge a slight influence of charge accumulation on the impulse flashover level can be found.The conclusions obtained can be used in the designing spacers for gas insulated installations.