Abstract: The buildingc s outer windows with a large heat transfer coefficient and a poor leak tightness are the key positions, where energy is consumed. It is pointed out that attention shall be paid to the design of outer windows; the overall effects of lighting, ventilation, heat insulation and energy- saving shall be taken into account during the design and construction of a building. The material and window having good energy- saving shall be popularized and construction management of windows shall also be enhanced.