The extensive application of power electronic devices makes DC systems and switching components widely connected to AC systems. The transient processes at different time scales are intertwined. This increases the difficulty of analyzing and controlling the power grid. An electromechanical-electromagnetic hybrid simulation for large-scale power grids can balance the problems of scale, accuracy, and efficiency in power system simulation effectively. This paper proposes a hybrid simulation interface technology based on the equivalent model applied to the distribution network. Specifically, the Norton/Thevenin equivalent model is used. Parallel interaction timing is applied. In addition, the Dq-120 method of extracting the fundamental wave phasor at the interface is improved and used at the interface. Finally, a simulation example with a 33-node distribution network verifies the correctness of the hybrid simulation interface. This work is supported by National Natural Science Foundation of China (No. 51707026) and National Key Research and Development Program of China (No. 2016YFB0900200).