Object Oriented Security - At present, the traditional substation auxiliary control system is faced with the following four problems: poor real-time capability to abnormal response, high dependence on people when solving malfunctions, the communication, deployment and expansion of different underlying devices, and the lack of security mechanism. To solve these problems or optimize the functions, an intelligent substation auxiliary control system is proposed. The system innovatively applies OPC UA to the construction of the auxiliary control system. First, through the use of OPC UA s unique object-oriented modeling method as well as the joint specification modeling of OPC UA and IEC61850, to solve the data communication problems caused by heterogeneous devices. Second, applying the Client/Server mode to realize the remote access from authorized mobile clients and give instructions, to cope with abnormal conditions, which reduces the dependency on people. Clients of other authorized enterprises are allowed to access the working data of the devices they are interested in, makes full use of massive data and ensures the information security of the system. Third, Pub/Sub mode is applied to enable the underlying devices to communicate directly with each other through the middleware, which reduces the response time of equipment joint debugging and improve the real-time performance. In addition, through OPC UA, the industrial data of the system can be transmitted over the Internet, realizing the combination of the Internet of Things and the Internet, which is an idea of the combination of the two in the future.