The invention discloses a CIM/E file-based self-adaptive modeling method of an online monitoring system for secondary equipment. The system comprises a CIM/E model subsystem, a communication subsystem, a real-time library and a history storage subsystem, wherein the CIM/E model subsystem is used for realizing the model analysis and conversion of an online monitoring file; the communication subsystem is used for realizing master-slave station communication functions such as request and response; the real-time library is responsible for operation data refreshing and model management; and the history storage subsystem is used for completing the history storage and query of models. According to the system, CIM/E is adopted to describe a data exchange way of a whole-network model of the online monitoring system for the secondary equipment, universal real-time communication service protocols of electric power systems are used for providing network transmission of the models, and self-adaptive modeling is carried out on the system on the basis of a model comparison rule algorithm. Through a specialized CIM/E format of the electric power systems, a template is used for realizing the self-adaptive modeling method of the online monitoring system for the secondary equipment, so that the efficiency and usability of the system are enhanced.