The invention relates to a plastic rack heat resistance observation device which comprises a movable plate, wherein an observation box is arranged on the movable plate; a sealing cover is arranged at the end part of the observation box; a temperature control box is arranged in the observation box; a sealing door is arranged at the front side of the observation box; an observation window prepared from a glass material is arranged on the sealing door; temperature controllers are arranged on the movable plate; electrical heating bars are arranged on cushion blocks; electric heating wires are arranged on the outer surfaces of the electrical heating bars; the electric heating wires are arranged at outer side wall positions of the temperature control box; the electric heating wires are electrically connected with the temperature controllers. The plastic rack heat resistance observation device is convenient to control the temperature in the temperature control box; by the observation window, heat resistance of a plastic rack can be simply observed.