Today, the shortage of information about the different sections of organization is not the main challenges of managers and organizations. But, the ways to handle the huge amount of generated information for solving different problems of organization and decision making are main difficulties. Information technology (IT) can provide effective tools that help organizations to address such problem. In today’s competitive business environment, significant investment in IT is becoming an important source of competitive advantage and operational efficiency. Companies are implementing tens of millions of dollars at a time to implement Enterprise Resource Planning (ERP) or Customer Relationship Management (CRM) technologies in hopes of achieving dramatic improvements in an organization’s efficiency. By using information systems, managers will have the capability to effectively manage different aspects of supply chain. And also the capabilities of E-commerce will be improved. Information systems software packages like MRPII and ERP help companies to streamline their processes and empower them with a better control of data. The main advantages of enterprise systems are improved coordination across functional departments and increased efficiencies of business processes. Despite numerous advantages of these systems, many organizations face several difficulties in implementation process. With regards to these problems in this research by reviewing most common Critical Success Factors (CSFs), and challenges in literature of ERP and other information systems like MRPII, an appropriate method by combining Analytical Network Process (ANP) and DEMATEL technique under fuzzy environment, is proposed to evaluate and ranking of these CSFs. The proposed methodology is applied in an real case and results show that Project Team, Top Management Support and Vendor Selection are the three top CSF in case study.