The invention discloses a horizontal concrete sprayer, wherein, a feeding mechanism comprises a framework and a rotor material cavity which is rotationally arranged on the framework and connected with a driving mechanism in a driving mode; the rotor material cavity and a central revolving shaft thereof are arranged horizontally; a material cavity body enclosed on the outer circumference of the central revolving shaft is a groove-typed material cavity body in which a plurality of groove openings are cut on the circumferential surface and the length direction of the groove openings extends in an axial direction; the feeding mechanism also comprises cylinder shell-shaped stators which are sleeved on the outer circumferences of all the groove-typed material cavity bodies of the rotor materialcavity and fixed on the framework; a sealing device is arranged at the joint where the circumferential surface and the end surface of the rotor material cavity are jointed with the stator; a feeding port matching with a hopper is cut at the upper part of the circumference of the stator; and an air inlet pipe and a discharging pipe are inserted into the stator so as to match and communicate with the same groove-typed material cavity body of the rotor material cavity. The groove-typed material cavity has larger groove opening area, shorter concrete running time in the material cavity and smoothdischarging without blocking the discharging port of the hopper. The discharging and charging speeds are fast owing to the larger groove opening area.