With the continuous connection of multi-energy to the power grid, simulation research on the multi-energy long-term transmission system has attracted increasing attention. To further improve simulation efficiency and realize large-scale simulation of a multi-energy long-distance transmission line system, a simulation interface algorithm is proposed based on a long-distance transmission line model method. Also, given the delay problem in the iterative calculation of electromagnetic transients, a method for delaying compensation of the segmentation interface is proposed. This gives the system higher simulation accuracy during simulation. The controlled source is used as the control object of the split interface in the model interface algorithm, and the actual multi-energy and multi-voltage long-distance transmission line system is used as an example to be verified in a Matlab/Simulink, real-time simulator (UREP_300) and RT-LAB simulation platform. The results show that the designed long-distance transmission line model (TLM) interface algorithm is basically consistent with the transient and steady-state results of distributed wiring for long-distance system transmission, and the interface algorithm is suitable for offline simulation and real-time simulation platform. This offers advantages in improving simulation efficiency.