The invention relates to a valve baffle plate opening device for a fixed contact box in an armored run-out type switch cabinet. The valve baffle plate opening device comprises a switch tray, a transmission arm and a permanent magnet connector arranged at the front end; a roller pin shaft is arranged on a transmission crank arm and is provided with a roller; a chain-type transmission arm is arranged on a chain-type transmission arm sliding guide rail; left and right sliding shaft sleeves are arranged on left and right transmission crank arms and are fixed to two sides of a valve pushing shaft; left and right transmission plates of a valve are arranged on left and right guide rails of the valve; the left and right guide rails of the valve are arranged on left and right side plates of the switch cabinet; and the left and right guide rails of the valve are provided with left and right sliding shaft sleeve sliding tracks, lower contact box valve sliding tracks and upper contact box valve sliding tracks. The chain-type transmission arm is pushed by the transmission arm to push the valve pushing shaft to drive the left and right transmission plates to slide in two sliding guide rails, so that uniform and balanced stress on two sides of contact box baffle plates is ensured; the contact box baffle plates move in parallel; and the condition that the contact box baffle plates can be smoothly opened or closed simultaneously is ensured.