Research is lacking on the three-dimensional modeling of auxiliary equipment monitoring systems in substations, and the existing model has the problem that the size of a single device is too large to display the status, functions and movement of the equipment. Given that, a three-dimensional model of operation and maintenance management for auxiliary equipment in substations is explored and constructed, including modeling methods, modeling processes, and mapping relationships between 3D models and auxiliary control subsystems. On this basis, the interface and data interaction between the three-dimensional model base and the three-dimensional plug-in are defined. A three-dimensional plug-in based on plug-in dynamic loading technology is developed to realize the interface between the three-dimensional control and the auxiliary control host, and display equipment status information and detection data on the three-dimensional model in real time. It also intelligently interacts with the alarm of the auxiliary control system, providing an intuitive and interactive monitoring human-machine interface for operational and maintenance personnel of the substation. This work is supported by Science and Technology Project of the Headquarter of State Grid Corporation of China (No. 5206/2018-19002A) “Research and Application of Intelligent Decision-making Key Technologies”.