The invention provides a method and a device for decomposing information system models in an electric power system. The method comprises the following steps: acquiring model information from the electric power system, and acquiring XML (X Extensible Markup Language) transmission data according to a preset interface; classifying the model information according to the acquired XML transmission data to obtain a preset quantity of regional networks; performing network region partition on a server host according to a server host type which is relevant to the regional networks; and comparing the quantity of information system models obtained after the regional network partition and a preset quantity, and combining data of the information system models according to a comparison result in order to keep the quantity of the combined information system models consistent with the preset quantity. Through adoption of the method and the device for decomposing the information system model in the electric power system provided by the invention, the problems of lowering of the computation processing speed and the system running speed caused by huge scale of a power grid and huge data throughput can be solved.