Abstract: The present invention relates to a non-flammable cushioning and sealing sheet and, more particularly to, a sheet having a sequential layered structure of an adhesive layer, a polyurethane layer, and a surface coating layer, the polyurethane layer containing melamine polyphosphate and diphenyl cresyl phosphate as a flame retardant. The present invention also relates to a method for preparing a non-flammable cushioning and sealing sheet that comprises: preparing a polyurethane layer containing melamine polyphosphate and diphenyl cresyl phosphate as a flame retardant; forming a adhesive layer on the one side of the polyurethane layer; and forming a surface coating layer on the other side of the polyurethane layer where the adhesive layer is not formed.