The invention discloses an ultrathin heat sublimation transfer paper. The ultrathin heat sublimation transfer paper comprises a base material, a binding agent and a coating coated on the surface of the base material, wherein the coating comprises carboxymethyl cellulose, sucrose, glycerol, starch, polyvinyl chloride resin, polyethylene glycol fatty acid ester, fumed silica, aluminum oxide, calciumcarbonate, a bactericide, a polysaccharide derivative, kaolin, titanium dioxide, sodium polyacrylate, bentonite powder and a dispersing agent. The invention further discloses a preparation method ofthe ultrathin heat sublimation transfer paper, the preparation method is that the materials of all the components is carried out dissolving, mixing, heating, uniformly stirring, and discharging by steps. According to the method, the polysaccharide derivative and glycerol are added, so that the paper surface is smooth, the phenomenon of bending deformation is not easy to occur, and the heat sublimation printing quality is improved, so that the application of the ultrathin heat sublimation transfer paper is realized, and the transfer rate of the produced paper is improved, and the application ofthe ultrathin paper in the field of thermal sublimation is improved.