The invention relates to a deep well drilling waterpower deslagging device of a floor anchor rod hole of a tunnel, which effectively solves the difficulties that the deslagging effect in the drilling process of a floor anchor rod hole drilling device and the increase of the drilling rate of the anchor rod hole is restricted. The invention has the technical scheme that a drill pipe both ends of which extend out of a sleeve is arranged in the sleeve, the upper end of the drill pipe is connected with an upper connector connecting piece, the lower end of the drill pipe is connected with a lower connector connecting piece, the upper end and the lower end of the drill pipe and the sleeve are fixed together via a closed-type bearing and a bearing sleeve connecting piece to form a deslagging structure with a dewatering and deslagging channel, the periphery wall of the drill pipe is provided with a spirally wound annular rib, a water inlet channel is arranged in the drill pipe, and the deslagging structures are connected with each other via a sleeve connecting pipe. The invention has the advantages of simple structure, convenient operation and good deslagging effect, greatly increases the drill rate and hole forming depth of the floor anchor rod, and is innovative on a deslagging device.