Aiming at the low-frequency oscillation of traction network caused by the high-speed railway electric motor units (EMUs), when transient current control strategy (TCCS) based on traditional PI controller is adopted by the line-side converter (LSC) of the EMUs, by analyzing the PI controller parameter adjustment, it is found that this suppression measure has its limitations. In order to overcome the above problem, this paper brings internal model control (IMC) into the TCCS, and according to the internal model control principle, a two-degree-of-freedom (2DOF) internal model controller is designed to replace the traditional PI controller in the TCCS. Then comparing the performance characteristics of TCCS based on traditional PI controller with TCCS based on 2DOF-IMC. Finally, the EMUs adopting the two control strategies are applied to the time-domain simulation model of the train-grid respectively, it can be found that TCCS based on 2DOF-IMC provides better tracing and load disturbance regulation characteristics, in addition, it is able to suppress the low-frequency oscillation of high-speed railway traction network effectively.