Abstract: Modern substations have strict requirements for the internal environment of the station. The numerous high voltage level primary equipment in the station can cause certain interference to the secondary system of the substation. Analyze the types of interference signals and the impact mechanisms of interference sources in the secondary system during the operation and use of the substation project, in order to demonstrate the necessity of grounding renovation of the secondary system in the substation. And elaborate on the content of the grounding renovation technology plan for the secondary system of substation relay protection from multiple aspects, and propose specific strategies for the grounding technology of the secondary system. Intended to improve the secondary system grounding technology system and achieve the goal of standardization and application of grounding technology. Provide technical guidance for the development of secondary system grounding renovation plans.