The invention discloses a window heat preserving platen which comprises a bottom plate, an activated carbon layer, a phenolic foam plate and a marble plate. The section of the bottom plate is in an L shape. The bottom plate, the activated carbon layer, the phenolic foam plate and the marble plate are sequentially connected in a sealed mode from bottom to top. An electric heating wire is arranged in the activated carbon layer and is in a wavy shape. One side of the electric heating wire is provided with a power connector which is electrically connected with the electric heating wire. A plurality of round holes are formed in the phenolic foam plate and distributed at equal intervals. A rivet is arranged on one side of the bottom plate. A metal head is arranged at the tail end of the rivet and is in a hemispherical shape. The metal head and the rivet are integrally formed. The left side of the marble plate is inclined. The left side of the marble plate is provided with a sealing plate which is connected with the bottom plate, the activated carbon layer, the phenolic foam plate and the marble plate in a glued mode. The window heat preserving platen is good in heat preserving effect, has a heating function, and is high in structural strength and convenient to install.