This study was conducted with the general purpose of analyzing the key factors affecting the implementation of the core banking system in one of the Iranian banks.In this study, the key factors affecting the success of core banking systems implementation were identified, among which were five key factors supporting the senior manager, the best methods of project management, business process re-engineering, final user training and support of vendor is the main effect of the study selected and its effect on the implementation of the core banking system has been studied. The results of the study indicate that the support of top management and the best project management method have had the greatest impact on the success of the core banking system implementation, and other factors have not had any effect on its success and implementation.