Nowadays, China’s electrified railway technologies were in the alternating stage. AC-DC and AC-DC-AC locomotive (CRH) running in mixture led to rich harmonics in the traction power supply system. Harmonic elimination technology in electrified railway at home and abroad was introduced, and status of specified harmonic current friquency dividing control was focused on; Low-order and high-order harmonic distribution was also analyzed considering of electrified railway power supply characteristics; Combined passive high-pass filter with harmonic suppression technology of railway power controller (RPC) based on a modular multilevel converter (MMC) topology, harmonic suppression strategy for traction power supply system to achieve the specified harmonic and high harmonics suppression was proposed. A simulation model was built in the RT-LAB platform and simulation results showed the validity of the control strategy.