The utility model relates to a sliding block of a stacker. The sliding block is arranged in a chute of a sliding rail in a sliding way; a guide rod is arranged between the sliding block and the sliding rail; the sliding block comprises a top mounting plate, an upper mounting seat, a lower mounting seat and a bottom pulley group, wherein the top mounting plate is fixedly connected to the upper surface of the upper mounting seat; the upper mounting seat is fixedly connected with the lower mounting seat; rack blocks and connecting insertion columns are fixedly connected between the upper mounting seat and the lower mounting seat; the rack blocks are symmetrically inserted into two side parts of the lower surface of the upper mounting seat; the bottom pulley group comprises a plurality of staggered pulleys; the pulleys are connected with the lower mounting seat via a screw shaft. The sliding block of the stacker has the advantages of simple structure and convenience in installation. The adopted independent rack blocks are convenient to replace and low in cost, and the sliding block can stably and smoothly work by the cooperation transmission of worms and racks.