With energy-saving and emission-reduction have become the theme of today's social development, the theoretical design and research of novel transparent heat insulation materials for windows, which can save energy and improve the comprehensive utilization efficiency of solar energy, are particularly crucial.In this paper, a calculation method based on DFT(density functional theory) is used to study the lattice parameters (the geometric structure of h-WO₃ crystal was optimized by calculation) electronic band structure, formation energy, and optical properties of pure hexagonal phase tungsten trioxide(h-WO₃) before and after doping with Tl. The calculated results indicate that the lattice volume increases and the total system energy decreases to a negative value after Tl-doped h-WO₃, while the system has better stability; The electron band structure changes greatly after doping, but the material still maintains n-type conductivity. In the meantime, the optical properties of the material also changed, h-WO₃ had no near-infrared absorption performance before Tl-doping, and Tl_0.33WO₃ after Tl-doped had strong near-infrared absorption performance. On this basis, the solar radiation shielding performance of h-WO₃ before and after Tl doping has been studied. The results show that pure h-WO₃ has no solar radiation shielding performance, while Tl_0.33WO₃ thin films after Tl-doped h-WO₃ have high transparency in visible light region and strong absorption in near infrared radiation. The calculation results provide a theoretical basis for the application of transparent thermal insulating material for windows of Tl-doped h-WO₃.