Today, knowledge and information are considered as determining factors in the success and competitiveness of organizations. Products and services of those businesses that can efficiently obtain knowledge in organization and use it in business processes will have a competitive advantage on the market. In this study, the fuzzy DEMATEL technique was used to examine the causal relationships between factors affecting the implementation of knowledge management, and the fuzzy ANP technique was used to determine the priority of factors. The case study in this research is of the Tehran Fire Department (TFD). The results showed that during the implementation of the fuzzy DEMATEL method, "specified strategies and objectives in the use of knowledge management" was the most influential factor and the factor of "designing effective processes to apply KM" was the most impressible one. Finally, using fuzzy ANP, “strategies and specific objectives in the use of knowledge management” was determined as the most important factor.