The utility model relates to a shim plate for a furnace bottom plate of an annealing furnace. A circular metal plate (2) of which the thickness is 20 to 60 millimeters is additionally arranged on a furnace bottom plate (1). The utility model can prolong the service life of the furnace bottom plate, reduce production cost, diminish the width of side waves, have no imprint and make the performance and the quality of products accord with the standard.