As the idea of low carbon, green, environmental protection and ecology becomes the civilization symbol of modern city, thermal insulation materials in buildings, as an effective way to reduce energy cost in architecture, have attracted numerous attentions up to now. In the present report, DeST-h software was adopted to investigate the energy saving model, which can save 75% energy cost, used in 6-floor housing in Beijing. The heat transfer coefficient (K) was calculated to be 0.40 W m^-2 K^-1, which means it can save about 42.31 kW h^-1 m^-2 per square meter. Based on these calculations, it was found that 17.09 kg coal can be saved per square meter area in the building, resulting in reducing 42.19 kg carbon dioxide (CO₂), 1.27 kg sulfur dioxide (SO₂), 0.635 kg nitrogen oxide (NO_x), 11.5 kg coal powder dust and 5.75 kg coal smoke dust emission per square meter area in the building. These reductions generate -36.66 RMB profit per square meter area in building. In addition, the total energy savings of the four common thermal insulate materials (rock wool, XPS, EPS and Polyurethane) in 50 years was respectively calculated to be 6.55×10⁶, 6.63×10⁶, 6.58×10⁶, 6.77×10⁶kJ/m² based the theory of LCA. Furthermore, the energy consumption proportion differs at different stage. The largest one is operation energy consumption and followed by production energy consumption and transportation energy consumption. In addition, the total capital payback period of thermal insulator materials, environmental benefits and energy saving of these four kinds of materials are also different from each other. The longest capital payback period is found to be polyurethane and followed by XPX and EPS, and the shortest one is rock wool. What's more, the scientific evaluation and the developing trends on building's exterior all thermal insulation materials were also outlined in this report.