Abstract: With the accelerated advancement of the digitalization and Intelligentization of substations, the traditional secondary circuit design method based on CAD drawings can no longer meet the needs of modern power grid construction and operation and maintenance. This paper conducts an in-depth study on the key technologies and application effects of secondary circuit modeling in substations, and elaborates in detail the entire process from data collection and model construction to visual display. The research shows that the digital modeling of secondary circuits can significantly improve efficiency, provide technical support for the whole-life cycle management of substations, and is of great significance for promoting the digital transformation of power grids.