Underground drainage backstop for coal mine

The utility model belongs to the technical field of coal mining, and particularly provides a coal mine underground drainage backstop which comprises a conducting pipe, two fixing pieces, a sliding plug, a first spring and a reversing alignment mechanism, the two fixing pieces are fixedly installed in the conducting pipe, the sliding plug is connected with the two fixing pieces in a sliding mode, and the first spring is connected with the reversing alignment mechanism. Rubber sealing rings are arranged on the contact faces of the sliding plugs and the fixing pieces, first springs are connected between the sliding plugs and the fixing pieces on one side, the reversing alignment mechanism is arranged outside the conduction pipe, the geometric center of the conduction pipe is rotationally connected with the geometric center of the reversing alignment mechanism, and the fixing mechanisms are assembled on the two sides of the reversing alignment mechanism. The fixing device is used for fixing the reversing alignmen