In this paper we present the development of CITIS(Contractor Integrated Technical Information Service) reference model system which can be utilized for electronic commerce among enterprises. For the physical analysis target model, we selected switching system businesses of Korea Telecom. From analysis of life-cycle business process and data, we derived CITIS reference model containing CITIS To-Be model and CITIS scenario. Derived CITIS reference model is generalized so that it can be used not only for switching system businesses but other business areas regarding CITIS implementation. On the base of the derived CITIS reference model, We also developed CITIS information management system and CITIS-support workflow system as CITIS reference model system. Developed CITIS reference model system supports information and business process sharing among enterprises on internet and it does make a contribution to expansion of CITIS which is moving from conceptual research towards real implementation phase.