In the process of implementation of the reconstruction and expansion project, there are problems of vision control and design interaction when the original SCD file is updated. Combined with the international standard of IEC61850 Ed2, the automatic reconfiguration technology of the secondary system configuration files for the reconstruction and expansion project based on the SED file is proposed for the first time. In the reconstruction and expansion project, the local reconfiguration technology based on SED file is used to fully decouple the SCD file from the design and configuration process, which ensures the relative independence of the reconstruction and expansion. Through the rule definition mechanism of the SED file in the reconstruction and expansion project, it is guaranteed that the operation equipments will not be modified in the design stage of the reconstruction and expansion and the safety of the operation equipments is improved. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 61602251).