The utility model relates to a knife switch mechanism case, particularly relates to a knife switch mechanism case suitable for severe environments, and relates to the field of electrical equipment. The knife switch mechanism case comprises an external case body which is internally provided with an internal case body. A knife switch mechanism is installed in the internal case body. A cable penetrates through the external case body to be installed in the internal case body. An air inlet is arranged below the external case body. The internal end of the air inlet is provided with a fan. The side, which is opposite to the fan, of the external case body is provided with a heater. The upper part of the external case body is provided with an annular air exhaust port. The bottom part of the internal case body is provided with a temperature sensor and a humidity sensor. The internal case body is internally provided with an automatic control system. The knife switch mechanism case is high in environmental adaptability so that generation of phenomena of condensation and corrosion can be avoided and normal operation of the equipment is guaranteed.