The invention provides an automatic door special for preventing small animals from entering a transformer substation. The automatic door is used for preventing small animals from entering the transformer substation. The automatic door comprises a door frame. The door frame is hinged in the transformer substation in a side opening mode. An upper movable shaft, an outward-stretching shaft, a middle shaft, an inward-stretching shaft and a lower fixed shaft are arranged in the door frame in sequence from top to bottom. A first baffle is installed between the upper movable shaft and the outward-stretching shaft in a hinged mode. A second baffle is installed between the outward-stretching shaft and the middle shaft in a hinged mode. A third baffle is installed between the middle shaft and the inward-stretching shaft in a hinged mode. A fourth baffle is installed between the inward-stretching shaft and the lower fixed shaft in a hinged mode. A driving gear and a driven gear engaged with the driving gear are further arranged on the upper portion of the door frame. The driving gear and a second rope wheel are arranged coaxially and driven by a motor to rotate, and the driven gear and a first rope wheel are arranged coaxially; and pull ropes are wound on the first rope wheel and the second rope wheel correspondingly, and the two pull ropes are fixedly connected with the right end and the left end of the movable shaft correspondingly. By the adoption of the automatic door, small animals can be effectively prevented from entering a transformer room.