Cavity door fixing device

The invention discloses a cavity door fixing device which is applicable to fixing a cavity door on a cavity body wall and can realize unfixing. The device comprises a handle, a retaining piece and a spring, wherein the handle stretches out of a boss convexly, the boss stretches out of a connecting rod; the tail end of the connecting rod is provided with screw thread to form a screw thread part, the boss is provided with a first circular slot surrounding the connecting rod, the spring is penetrated through the connecting rod, one end of the spring is arranged in the first circular slot, and the other end of the spring stretches out of the first circular slot; the cavity door is penetrated with a mounting hole, the cavity body wall is provided with a threaded hole with internal thread and corresponding to the mounting hole, the connecting rod penetrates through the mounting hole, and the screw thread part stretches out of the mounting hole; the retaining piece is clamped on the connecting rod and positioned between the screw thread part and the boss; the retaining piece resists against the internal surface of the cavity door in a separation way; and the boss resists against the external surface of the cavity door in a separation way. The cavity door fixing device of the invention can share the oppression quantity of a sealing ring on the cavity door and ensure the cavity door not to fall off when the cavity door is opened.