Business environments have become much more complex, through the rapid development of information technology (IT) and knowledg. In order to overcome ensuing complications, enterprises ought to make changes about products, services and processes. Consequently, many enterprises have applied IT in order to cut production costs, introduce innovations in products and services, promote growth, develop alliances, lock in customers and suppliers, and create switching costs and raise barriers to entry. In other words, IT can help a firm aiming to gain a sustainable competitive advantage. In addition, many studies have argued that intangible assets such as knowledge can create business value. And therefore, knowledge workers will be able to replace clerical workers as the new mainstream of manpower resources, a field in which the development of IT is the main force for change in knowledge management system (KMS). Therefore, this study explores the role and effect of IT in the application of KMS on firms; moreover, relationships between KMS and IT are analyzed and demonstrated by means of the expert interviews, literature reviews, and questionnaire analyses. Also, how to enhance the effectiveness and efficiency of implementing KMS through appropriate IT is discussed by this study.