Effective use of organizational knowledge helps organizations foster innovation, reduce costs, improve decision making, and create sustainable competitive advantages. Knowledge Management (KM) is adopted by many organizations as a new approach for discovering and exploiting organizational knowledge as much as possible. According to the contingency theory, the successful implementation of knowledge management in an organization highly depends on choosing the best KM processes according to the organization’s circumstances. The purpose of this study is to evaluate the factors affecting the choice of the appropriate knowledge management process in the organization and ultimately prioritize the KM processes using a rule-based fuzzy system. The contingency factors that are studied in this research are those related to knowledge properties, organizational, environmental and task characteristics. Also, knowledge management processes that are considered are knowledge discovery, knowledge acquisition, knowledge sharing and knowledge application. The relationship between processes and contingency factors is modeled based on Fernandez method, using fuzzy rule-based systems. By evaluating and quantifying each of the factors, knowledge management processes are prioritized with respect to the input factors. The obtained results of prioritizing knowledge management processes by this method compared with previous researches shows a significant improvement.