Abstract: Currently, China is continuing to rapidly build a high-speed electrified railway network. The demand for high-speed rail loads to connect to the high-voltage-ultra-high voltage power grid is increasing. When they are connected to the power grid, however, harmonic current will be injected, subsequently causing voltage waveform distortion. In order to compare the evaluation methods for connecting the non-linear loads to the HV-EHV systems provided in the IEC/TR 61000-3-6: 2008 technical document and in the British G5/5 Engineering Guidelines, this paper takes the grid connection of a 220 kV high-speed rail traction station as an application case to compare and analyze the application effects of the two methods, which can will provide some references for the revision of China’s national standards for power quality harmonics.