This study aimed to build a model Investment Group Decision Support System (IGDSS) to evaluate the feasibility of investment information technology in government. The model builds upon many of the preferences given by a group of dicision makers that are the result of classification of risks, costs and benefits. Some prombelms will be solved in this research is: do the selection criteria to determine the risk, cost criteria and benefit criteria: (1) build the knowledge base on IGDSS; (2) build a model of inference to conduct feasibility analysis of IT investments; (3) build a model IGDSS of many preferences and a group of decision makers for making investment decisions and evaluation performance. Something nw and development models contained in this system are: (1) the concept of GDSS has never been applied for the benefit of the project feasibility analysis of IT investment in government that combines the benefit analysis, cost analysis and risk analysis with the concept of MCDM and MADM; (2) concept formation rule based on a group of decision makers preference for the feasibility of IT investment projects with a variety of formats has never modeled; (3) the concept of forming a knowledge base of project feasibility analysis of IT investment in government using MCDM and MADM has never modeled. Through the results of this study is expected to give benefit in enriching from of modeling in group decision support systems, especially in group decision making IT investment feasibility. Key words : Investment Group Support System (IGDSS), risks, costs, benefit, MCDM, MADM