The utility model discloses a device for automatically discharging the positive pressure water in a gas pipe. A water tank cover is positioned at the top of a water tank. A water outlet pipe is disposed at the lower part of the water tank. A drainage valve is hermetically connected with the water tank at the bottom of the water tank. A positioning sleeve is disposed at the lower end of the tank cover for spacing and supporting the upper part of a lifting rod. Upper and lower fixing members are fixedly connected on the upper and the lower parts of the lifting rod. A floater for reflecting variation of the water level is fixedly clamped. The upper clearance of the lifting rod is matched in the positioning sleeve, and the lower part is matched in the through hole of a filter cylinder with a plurality of draining holes at the periphery in a sliding manner. The upper end of the lower part of the lifting rod extends from a valve base center hole at the filter cylinder bottom and is connected with the water outlet pipe at the lower part of the water tank. The conical valve at the bottom end of the lower part of the lifting rod is arranged in the valve base center hole to seal the center hole. The device can automatically discharge the positive pressure water in a gas pipe to ensure the gas pressure in the pipeline; therefore, a large amount of man-power is reduced, and the cost is greatly lowered.