The invention provides a shielding device used for installation or maintenance in a highly-radioactive environment. The shielding device comprises a long rotating rod, a handle and a special-shaped shielding lead sheath, wherein the special-shaped shielding lead sheath is provided with a gap and arranged at the inner side of an exhaust channel; the initial end of the long rotating rod is vertically connected with the center of the special-shaped shielding lead sheath; the tail end of the long rotating rod penetrates through and extends out of the exhaust channel; the tail end of the long rotating rod is welded with the handle, and the direction of the gap of the special-shaped shielding lead sheath is regulated by rotation of the handle; a long rod sleeve pipe sleeves outside of the long rotating rod; and a plurality of cross supporting frames arranged in the interior of the exhaust channel support the long rod sleeve pipe. The shielding device provided by the invention has significantshielding effect, reduces gamma dose rate and shortens work period after applied in the highly-radioactive environment of a spent fuel element shearing hot cell.