In this paper,first,three assessment systems for green building,namely the LEED(USA) and GOBAS(China) are compared with CASBEE(Japan) in respect of central concepts,mark of evaluation and result of assessment.It is expected that this research of assessment systems could be helpful to designers of architecture in different specialties.Secondly,in this paper these three assessment systems are analyzed from the position of design work.In the end,it is pointed out that to compile a design-oriented handbook for green building design is the new domain of the assessment system for green building.