Successful implementation of Knowledge Management System (KMS) has been observed in many organization, where they use the system with real interest and enthusiasm. Despite of the fact, some organizations has failed to implement the KM initiatives to achieve its adequate advantages due to the lack of pertinent information and shortage of measurement that is used in KMS. The obstacles that hurdle the KMS implementation are some critical factors that must be taken into high precedence during KMS implementation. The critical factors that hindrance the KMS implementation can lead the organization to a poor KMS or fail its implementation. The main focus of this paper is to explore and investigate the critical success factors of KMS and analyze these factors for the success of its implementation. In this paper, we discuss the most prominent critical success factors of knowledge management system in the literature and compare these factors from different sources and their importance for the organization success.