Abstract: In order to reduce the carbon emission from buildings effectively and choice the technique of construction waste disposal and resource appropriately,a calculation method of building carbon emission was built on the basis of life cycle theory,and the carbon emissions of two public buildings in Beijing were quantitatively calculated. The results show that the carbon emission at their using phase accounts for82% and 89% respectively,and carbon emission at the building material production phase is 17. 3% and10. 4% respectively during the 50 years of life cycle. Then,according to the optimization of energy structure and green building energy-saving requirements in Beijing,the carbon emission reduction was calculated based on the scenario analysis,and the policy suggestions for reducing the carbon emission in public building areas were put forward. At last,the different scenarios of the construction waste disposal and recycling were analyzed and carbon emission at different scenarios was quantitatively calculated according to the current conditions of waste disposal in China.