Abstract: Determining the location of MOS is a comprehensive evaluation problem which is affected by various factors, it can be solved by Fuzzy AHP.The main factors which influence MOS's location are studied.A kind of evaluation index architecture determining MOS's location is put forward according to the affiliation between factors.IFAHP is used to determine the evaluation index's weight.In order to improve the accuracy of weight calculation and reduce computation amount, a new quantitative method named five-mark method is proposed to establish priority matrix.Example shows that IFAHP is fully applicable in determining MOS' location.