Information systems(IS) outsourcing has become a very important management strategy of implementing IS and many studies on the IS outsourcing approach had been performed in the organizations. But it isn't still show how to out source the IS functions and how to offer quantitative magnitude for judgement. To offer a quantitative decision model that can help practitioners set priority and reap the most benefits from outsourcing, we show outsourcing structure including 3 factors (strategic, economic and technological benefit) and sub-levels which is different from the Yang and Huang's model. Also, we compute the weight of alternatives using analytic hierarchy process to find a priority of the IS outsourcing. As a result of analysis, we suggest systematic steps and quantitative model to increase the precision of decision making. 1)