|Construction has been accused of causing environmental problems ranging from excessive consumption of global resources both in terms of construction and building operation to the pollution of the surrounding environment, and research on green building design and using building materials to minimise environmental impact is already underway. However, relying on the design of a project to achieve the goal of sustainable development, or to minimise impacts through appropriate management on site, is not sufficient to handle the current problem. The aim for sustainability assessment goes even further than at the design stage of a project to consider its importance at an early stage, before any detailed design or even before a commitment is made to go ahead with a development. Cost benefit assessment is one of the important contents in the green building assessment, based on the analysis of the cost and benefit items generated in the whole life cycle of green buildings, this study introduced the cost benefit assessment and the assessment tools. and put forward the increment cost and benefit of green building.