Abstract: The complex topology of cascaded power electronic devices brings huge computational pressure to electromagnetic transient simulation. The equivalent modeling method of the common-used modular multilevel converter (MMC) is relatively mature. However, a large number of complex new cascaded topologies have appeared in recent years, and there is still a lack of universal equivalent modeling methods. Therefore, this paper proposes a general equivalent modeling method for power electronic equipment which is suitable for the N-terminal submodule of any topology and cascading in any mode. The port characteristics of the original circuit are extracted by using the form of state space expression, and then the equivalent circuit model is reverse-constructed according to the obtained state space expression. The case study shows that the proposed method can not only improve the simulation efficiency by eliminating the internal nodes of the submodule, but also apply to the customized topology structure and cascading mode of the submodule, which is more flexible and general than the traditional equivalent modeling method. The existing modular multilevel converter (MMC) equivalent modeling method can be regarded as a special case of the general method proposed in this paper.