The fault distance calculation is one of most important parts in rapid restoration and repair of distribution system. Existing methods of fault distance calculation only consider unidirectional power flow characteristics of radial distribution system. However nowadays with the increasing connections of distributed generator, the distribution system is no more unidirectional rather bi-directional. Therefore, existing methods of fault distance calculation cannot be applied to distribution system with distributed generator. In this paper, a new fault distance calculation method is proposed for bi-directional characteristics of distribution system with delta connected transformer and distributed generator by using equivalent impedance. The method is verified in Simulink case system and results were found satisfying. Applying this method to distribution system with distributed generator, the improvement of reliability of distribution system will be expected.