The invention discloses a concrete spraying mechanical hand. The structure of the concrete spraying mechanical hand comprises a spraying head, a bearing table, a conveying belt, a moving joint, a large arm, a hydraulic cylinder and walking tracks. The walking tracks are installed on the two sides of the bottom of the bearing table correspondingly. The large arm and the hydraulic cylinder are installed at the left end and the right end of the top end face of the bearing table. The top end of the large arm is in movable fitting with the conveying belt through the moving joint. A spraying head ismovably installed on the bottom of the conveying belt. The spraying head is formed by an outer supporting frame and a discharging pipe. The outer supporting frame is movably installed on the outer surface of the discharging pipe. The discharging pipe and the conveying belt are in movable fitting. According to the concrete spraying mechanical hand, by means of common cooperation of the outer supporting frame, the discharging pipe and the like, the spraying head is flushed reversely so as to remove residues on the inner wall, impact force of water flow is enhanced for the second time, the washing effect is improved, during impacting or normal spraying, the triangle structure supports an extension ring stably, by means of the structural design of thread engagement, it is ensured that the discharging pipe does not shake, and the possibility of deformation caused by the impact force is reduced.