In this research, for the purpose of evaluating the performance of knowledge management systems as an improving infrastructure for organizational learning and performance in software development industry, a fuzzy inference system is designed and evaluated. At first, input variables were extracted as the performance evaluators of knowledge management system. Then, if-then rules were identified through the utilization of experts’ opinions and inserted to the fuzzy rule-base. The output of inference system was also designed for performance evaluation of knowledge management system. The designed system, through a comprehensive assessment of knowledge management systems, can enable organizations to identify the strengths, weaknesses, current condition, and future decisions making for the purpose of performance improvement. For the validation of fuzzy inference system, a comparison was made between system outputs and experts viewpoints. Considering the very small difference between the average of experts’ opinions and system output, it can be stated that the system has an appropriate precision and validity for future assessment.