In the past, decisions were made by senior management in organizations and they were based solely on personal experience, leading to increased risk in decision making. Nowadays, however, most companies are moving towards Business Intelligence (BI) systems. It is estimated that technology budgets dedicated to Business Intelligence in 2006, increased from $ 14 to $ 20 billion. Experiments have shown that the probability of failure in BI projects is high and evaluation before the start of implementation is important because if the company is not assessed, the implementation of BI projects can cause a waste of time and resources and the company will not achieve expected profits. The aim of this paper is to provide a method to evaluate the key factors for the successful implementation of BI projects and to determine the organization's index of assessing readiness before the implementation of BI projects. A series of technical and organizational key factors for the successful implementation of BI have been proposed in various literatures. These key factors will be evaluational ones for an organization. We apply a combination of Interpretive Structural Modeling (ISM) and Graph Theory and Matrix Approach (GTMA) on the factors to earn an indicator for evaluating the organization's readiness for implementing a BI project. We applied this method in two organizations for comparing and determined the organizations' readiness before the implementation of BI and found it to be very effective.