The invention relates to an auxiliary device for a drilling hole for gas drainage, in particular to a device for pumping and draining water from a downward hole of a coal bed, which solves the problems that the accumulated water in the downward hole of the coal bed cannot be drained out in time to influence the effect on gas drainage. The device comprises a liquid draining and pumping pipe, a drilling hole sealing device, and a drainage device provided with a first gate valve and a second gate valve, wherein the upper part of the drainage device is provided with a water inlet and a ventilation bolt of the drainage device, while the lower part is provided with a drainage bolt; the upper end of the drilling hole sealing device is connected with a hole connecting device; the upper end of the liquid draining and pumping pipe is extended in the hole connecting device, and a liquid guiding pipe is connected between the liquid draining and pumping pipe and the water inlet of the drainage device; and one side of the hole connecting device is provided with a first embedded wire pipe, and the second gate valve of the drainage device is connected with a second embedded wire pipe communicated with a gas drainage pipeline. The device can quickly and effectively drain out the accumulated water in the drilling hole to ensure the normal drainage and pumping of the drilling hole, improve the draining and pumping effect of the downward hole (or the drilling hole of a lower adjacent layer) of the coal bed, and reduce the gas content of the coal bed (or the lower adjacent layer) on a working surface; besides, the device has a simple structure and convenient connection and operation.