The invention relates to a protective pressing plate limiting insulation sheath. The protective pressing plate limiting insulation sheath comprises a fixing shell; two clamping devices are installed at the periphery of the middle of the fixing shell; the two clamping devices are arranged oppositely; the clamping device comprises a nut, a bolt, a butterfly handle, a rubber pad, a heat insulating pad and a heat insulating protrusion block; the bolt is installed on the fixing shell; the bolt is provided with the nut; and an end portion of the screw rod of the bolt is located at the inner side of the fixing shell. According to the protective pressing plate limiting insulation sheath of the invention, the two clamping devices can press a relay protective pressing plate through the heat insulating protrusion blocks after the relay protective pressing plate is connected with the protective pressing plate limiting insulation sheath, so that the relay protective pressing plate can be in close fit with the protective pressing plate limiting insulation sheath, and therefore, personal injuries and damage to a power grid and equipment caused by poor contact by the protective pressing plate can be avoided.