In thin-layer heavy oil reservoir, severe steam channeling leads to low sweep range, while limited temperature in aqueous displacing fluid restricts its thermally-induced viscosity reduction performance. To alleviate the above-mentioned problems, in this work, a high-temperature clayey sol Bent/PAANa was synthesized to enhance thermal efficiency and alleviate environmental hazards, with bentonite (Bent) applied as the matrix and sodium polyacrylate (anionic polyelectrolyte, PAANa) as the crosslinker. Wherein, the clay platelet percolated network on outer layer of Bent/PAANa sol provides a thermal-insulation coating and lubricating layer, effectively raising the sol temperature and fluidity in pay zone. Meanwhile, the polyanion-clay composite network within the sol endows it with high viscosity, significantly strengthening the displacement efficiency and profile control performance. From core flooding experiments, compared with steam drive, a higher sweep efficiency, displacement pressure and oil recovery was obtained, up to 27.2%, 169 kPa and 38.2%OOIP, after Bent/PAANa sol injection.