There are a huge number of harmonics in the railway power supply system. Accurately estimating the harmonic impedance of the system is the key to evaluating the harmonic emission level of the power supply system. A harmonic impedance estimation method is proposed in this paper. which takes the Gaussian mixture regression (GMR) as the main idea. https://www.roneverhart.com/Western-Digital-Ultrastar-DC-HC550-WUH721816ALE6L0-0F38460-16TB-7-2K-RPM-SATA-6Gb-s-512e-ISE-3-5in-Hard-Drive/