The invention relates to an insulation blocking type high-voltage direct-current relay and a working mode thereof. The insulation blocking type high-voltage direct-current relay comprises a copper column and copper pieces contacting with two sides of the copper column and is characterized in that a double-iron-core electromagnet is arranged at the lower end of the copper column and comprises an inner iron core, an outer iron core, coils and a static iron core, the lower end of the outer iron core is arranged in a groove in the upper end face of the static iron core, the top end of the outer iron core is provided with outward extension parts, large springs are arranged between the extension parts and the upper end face of the static iron core, the inner iron core is arranged inside the outer iron core and can move axially, a small spring is arranged between the inner iron core and the static iron core, the upper end face of the inner iron core is provided with an insulation blocking column which is located right below the contacts of the copper pieces and the copper column, and the coils are mounted inside the static iron core. The insulation blocking type high-voltage direct-current relay is simple in manufacturing process, short in production cycle, low in cost, free of explosion danger, and the like.