The invention relates to an automatic waterproof door and belongs to the technical field of stationary type or movable type closed devices used for opening positions of buildings, vehicles, fences or similar surrounding objects. The automatic waterproof door comprises a threshold, a door leaf, a trigger device and a waterproof device. The threshold is arranged on the ground outside the door leaf. The trigger device comprises a U-shaped pipeline and a floater, wherein the U-shaped pipeline comprises a first straight pipe and a second straight pipe, the second straight pipe is longer than the first straight pipe, the first straight pipe is arranged outdoors, and the second straight pipe is arranged indoors. The floater is placed in the second straight pipe. The trigger device further comprises a vertical rod, one end of the vertical rod is connected with the floater, the other end of the vertical rod is connected with a single pole switch, the single pole switch is electrically connected with the threshold, and the threshold is foldable. According to the technical scheme, the problem that rainwater in rainy days enters into the indoor space through a door seam can be effectively solved, and circuits are arranged indoors, so that the situation that the rainwater makes contact with the circuits, and short circuit occurs can be effectively avoided.