Building carbon emissions is an important indicator of green building evaluation. Calculate the carbon emissions of green building in the construction and operation period of great importance. On the basis study of the green building carbon calculator from University of Kansas professor KYGKwok,the paper introduce the relationship between carbon emissions and expound green building with carbon emissions calculator principles. Finally, according to China's actual conditions，the paper modify carbon calculator carbon emission parameters and application life-cycle theory to measure the carbon emissions of materials for their application in domestic carbon emissions calculations provide theoretical support of green building.