The invention provides a horizontal stacker and a control method thereof, and belongs to the technical field of glass manufacturing. The horizontal stacker comprises an abjusting device, an edge position detecting device, a grip, a bearing table and a control device. Through the abjusting device, the horizontal stacker realizes aligning and stopping, in a movement direction perpendicular to a production line, of glass plates; the edge position measuring device measures the distance of the edge of the outer side of each glass plate, so that coordinate positions of each glass plate are established; the control device controls the grip to move to the center position of each glass plate to grip and transfer each glass plate onto the bearing table of preset stage to stack, so that one horizontal stacker stacks multiple glass plates, and therefore, an equipment utilization rate is increased, waste of resource and space is avoided, and development of industry is promoted. The invention also provides a control method which can quickly and accurately realize coordinate positioning of each glass plate on the production line, and controls the grip to accurately grip the glass plates onto thecorresponding bearing table to stack, so that stacking efficiency is higher.