The invention discloses a horizontal coating device for preparing an HIT crystalline silicon solar cell, which comprises a cell, a tank body, a transmission mechanism, an anode mechanism, a cathode mechanism, a spraying mechanism, an inflating mechanism, a waste discharging mechanism, a circulating filtering mechanism and a liquid blocking mechanism, the anode mechanism and the cathode mechanism are arranged in the tank body and are connected with the rectifier to generate an electric field, the spraying mechanism, the inflating mechanism and the circulating filtering mechanism uniformly deposit copper ions in the tank to grid line electrodes of a plurality of columns of battery pieces, and the circulating filtering mechanism is connected into the spraying mechanism after being circularly filtered by the circulating pump and the filter through the overflow gathering port. And the inlet section and the outlet section of the tank body are respectively provided with a liquid blocking mechanism. By adopting the horizontal coating, the conversion process of battery pieces at the feeding and discharging ends of electroplating equipment between the horizontal direction and the vertical direction is omitted, a hanging tool is not used, the piece breaking rate is reduced, the electroplating quality is improved, the production yield is increased, and the labor cost and the production cost are reduced.