The present invention relates to an implementation method suitable for an electromagnetic transient multi-time scale real-time cnsimulation interface, said method comprising the following steps: according to an electromagnetic transient multi-time scale, dividing a simulation system into a plurality of sub-networks connected via decoupling element transmission lines, and determining time scales of the sub-networks; via a Thévenin equivalent circuit, breaking down a decoupling element into two controlled sources having fixed internal resistances, incorporating into the sub-networks, and performing network matrix initialisation; performing simulation calculation, and receiving data of an FPGA platform; pre-processing the data of the FPGA platform, obtaining intermediate variables, and continuing the simulation calculation.