There are many methods for model representation in DSS generator，such as first order logic， knowledge abstractions，macro，relational framework，and soon．All of these methods ignore the important components of model：expression，which is the basis of mode1．This paper presents a new method to represent model in DSS generator．M od els in DSSg can be viewed as having three levels：Theoretical model，Attribute mod el，and Value mode1．This three level model must be represented in DSSg．A DSSg named as 3 DSSg have been developed based on 3 level model representation method and have been used to developspecific DSS